THE  CULTURE  AND  DISEASES 
OF  THE  < 


USED 


J.J.TAU 


UNIVERSITY  OF  CALIFORNIA 
AT  LOS  ANGELES 


OTHER  WORKS 
BY  THE  SAME  AUTHOR 


DISEASES  OF  TRUCK  CROPS  AND  THEIK  CONTROL 
[In  Preparation] 

DISEASES  OF  GREENHOUSE  PLANTS 
[In  Preparation] 

DISEASES  OF  THE  SWEET  POTATO 
[In  Preparation] 


E.  P.  DUTTON  &  CO 

NEW   YORK 


V  V 

'  V 


?s  •*•••--•    •»• 


THE  CULTURE  AND  DISEASES 
OF  THE  SWEET  PEA 


BY 
J.  J.  TAUBENHAUS,  PH.D. 

Plant  Pathologist  and  Physiologist  in  Charge.     Expetimen 
Station,  Agricultural  and  Mechanical  College  of  Texas 


NEW  YORK 

E.  P.  DUTTON  &  COMPANY 

$81  FIFTH  AVENUE 


Copyright,  1917 
By  E.  P.  BUTTON  &  COMPANY 


PRINTED   IN    THE  UNITED   STATES   OF    AMERICA 


SB 
413 


TO 

THE  REVEREND  CHAIM  HIRCHENSOHN 

WITH   LOVE  AND   DEEP  AFFECTION 


194165 


PREFATORY  NOTE 

The  keen  appreciation  of  the  public  of 
the  beauties  of  nature  as  expressed  in  the 
building  of  parks  and  public  gardens,  in 
the  planting  of  street  trees,  and  in  the 
adornment  of  private  grounds  and  homes 
by  means  of  ornamental  plants  is  one  of 
the  most  distinctive  marks  of  an  advanced 
civilization.  The  success  of  these  under- 
takings means  the  overcoming  of  many 
difficulties  which  the  casual  observer  fails 
to  appreciate.  It  means  not  only  the  se- 
lection and  arrangement  of  varieties  in 
such  manner  as  to  meet  with  the  most 
aesthetical  tastes  of  the  public,  but  it  fre- 
quently means  growing  the  plants  under 
new  environmental  conditions,  the  study 
of  soil  and  climate,  the  contest  against 
insects  and  diseases  which  continually 
threaten  the  existence  of  these  plantings. 


Vll 


viii  PREFATORY  NOTE 

It  has  long  been  known  that  unfavor- 
able soil  and  climatic  conditions  and  de- 
structive insects  were  very  important  fac- 
tors in  plant  culture,  but  it  is  only  within 
recent  years  that  the  public  has  begun  to 
appreciate  that  many  of  the  difficulties  in 
growing  plants,  in  fact,  many  of  the  fail- 
ures are  due  to  diseases.  Most  of  these 
diseases  are  due  to  fungus  or  to  bacterial 
organisms.  Since  most  of  these  organisms 
are  so  small  that  they  cannot  be  seen  ex- 
cept with  the  aid  of  a  microscope,  the 
grower  has  usually  attributed  the  disease 
to  other  causes.  The  appreciation  of  these 
facts  makes  a  work  on  the  growing  of  any 
group  of  ornamental  plants  in  which  the 
importance  of  the  control  of  the  diseases 
is  given  a  prominent  place  very  desirable. 
Therefore,  this  work  on  the  Growing  of 
Sweet  Peas,  by  a  worker  who  has  made  a 
special  study  of  the  diseases  is  very  timely. 


PREFATORY  NOTE  ix 

The  sweet  pea  is  a  favorite  flower  with 
the  great  majority  of  people.  It  is  en- 
joyed by  both  the  high  and  the  lowly,  and 
is  within  the  reach  of  all.  It  is  a  profuse 
bloomer  and  presents  an  untiring  variety 
of  sizes  and  delicate  colors.  It  is  well 
adapted  to  various  conditions  and  can  be 
grown  over  a  very  large  part  of  the  world. 

The  author's  training  in  plant  pathology 
and  his  large  experience  with  diseases  of 
ornamentals  is  a  guarantee  of  meritorious 
character  of  the  work.  The  work  is  both 
practical  and  scientific;  it  is  equally  use- 
ful to  the  layman,  the  commercial  grower 
and  to  the  scientist;  it  deals  not  only  with 
the  diseases  of  sweet  peas,  but  with  the 
cultivation  and  other  important  questions 
connected  therewith. 

MEL.  T.  COOK. 
Rutgers  College, 

New  Brunswick,  N.  J. 
January,  1917. 


PREFACE 

The  sweet  pea  is  unfortunately  one  of 
those  crops  which  has  received  scant  con- 
sideration in  horticultural  text  books. 
The  field  to  be  covered  by  the  latter  is  so 
large  that  their  treatment  of  many  a  crop 
is  necessarily  meager.  Good  articles  on 
the  culture  of  the  sweet  pea  are  to  be  found 
in  various  journals,  but  are  not  accessible 
to  the  practical  grower.  The  cultural  di- 
rections which  seed  concerns  publish  for 
the  benefit  of  their  patrons  are  brief;  and 
Mr.  Harrison  Dick's  "Sweet  Peas  for 
Profit"  covers  only  one  phase  of  the  sub- 
ject, namely,  the  greenhouse  culture.  As 
no  complete  study  of  the  sweet  pea  has 
been  published  in  America,  it  is  felt  that 

this  book  may  be  very  timely,  especially 
xi 


xii  PREFACE 

since  this  delicate  flower  is  gaining  so  rap- 
idly in  popularity. 

The  chief  difficulty  encountered  by  the 
growers  of  the  sweet  pea  is  the  combating 
of  diseases,  in  which  they  have  had  very 
little  help.  Massee  and  Chittenden  in 
England  have  devoted  some  time  to  the 
"Streak  disease,"  but  these  workers  have 
been  misled  in  their  observations  by  at- 
tributing this  disease  to  the  fungus  Thie- 
lavia.  In  the  United  States,  floral  pathol- 
ogy is  still  in  its  embryonic  stage,  and  the 
sweet  pea  was  not  the  first  to  claim  the  at- 
tention of  Pathologists.  The  author  of 
this  book  in  the  last  three  years  has  pub- 
lished several  papers  on  his  own  investi- 
gations, taken  up  largely  because  of  nu- 
merous complaints  from  growers  who  met 
with  failure  in  their  attempts  to  grow  this 
beautiful  flower.  Florists  and  gardeners 
have  often  been  hopelessly  discouraged 


PREFACE  xiii 

the  first  time  they  tried  to  grow  sweet  peas 
because  of  total  loss  from  disease.  Others 
who  have  grown  them  for  years  have  been 
meeting  with  difficulties  that  are  consider- 
ably reducing  their  profits.  The  layman, 
particularly  the  housewife  so  proud  of  her 
row  of  sweet  peas  by  the  house,  has  seen 
many  of  them  carried  off  by  blights  and 
the  remainder  dry  up  and  wither  away. 

Naturally  the  blame  fell  at  once  on  the 
seedsman,  who  was  accused  of  supplying 
a  poor  grade  of  seed.  In  seeking  justifica- 
tion, seedsmen  attributed  the  growers' 
failures  to  bad  weather,  to  drought,  or  to 
the  green  aphids.  A  few  seed  catalogues 
and  some  popular  articles  on  the  culture 
of  the  sweet  pea  asserted  that  the  plant  is 
unusually  free  from  disease,  and  that  all 
failures  are  due  to  overfeeding.  Many 
practical  men  do  not  realize  that  plants 
have  diseases  just  as  do  animals  and  hu- 


xiv  PREFACE 

man  beings.  We  shall  here  endeavor  to 
show  that  although  bad  weather,  over- 
feeding, etc.,  may  be  important  factors, 
they  are  not  the  fundamental  reasons  for 
failure.  We  shall  study  the  specific  causes 
that  lead  to  the  diseases  of  the  sweet  pea; 
the  definite  parasitic  forms  of  life  such 
as  insects,  fungi,  and  bacteria  that  live 
upon  this  plant  and  bring  about  its  de- 
struction. The  nature  of  the  attacking 
insects  is  still  incompletely  known  and 
there  is  urgent  need  of  further  investiga- 
tion of  them.  Of  the  fungi,  nine  produce 
serious  diseases  in  either  roots,  stems,  foli- 
age, or  blossoms  of  sweet  peas.  Only  one 
bacterial  trouble,  however,  is  so  far  known 
to  affect  sweet  peas,  and  that  is  the  dreaded 
"Streak."  To  these  troubles  may  be  added 
eel  worm,  red  spider,  and  mites,  all  of 
which  add  considerably  to  the  losses. 
In  the  discussion  which  is  to  follow, 


PREFACE  xv 

technical  terms  as  far  as  possible  will  be 
avoided,  with  the  exception,  however,  of 
the  scientific  names  of  the  parasites.  Pop- 
ular terminology  does  not  always  distin- 
guish between  diseases  of  different  nature 
that  are  apparently  alike.  For  example, 
the  term  "blight"  is  applied  to  diseases  of 
similar  symptoms  but  of  quite  different 
causes.  Methods  of  controlling  a  disease 
are  directly  dependent  on  a  knowledge  of 
the  nature  and  cause  of  the  particular 
trouble.  Taking  insect  pests  as  an  exam- 
ple, it  is  essential  to  know  whether  they 
are  biting  or  sucking,  each  class  requiring 
different  treatments. 

The  writer  feels  that  no  apology  is 
needed  for  allowing  space  in  this  book  to 
a  discussion  of  the  culture  of  the  sweet 
pea.  No  matter  from  what  angle  we  look 
at  it,  we  cannot  deny  the  fact  that  plant 
diseases  are  directly  dependent  on  the  cul- 


xvi  PREFACE 

tural  conditions  of  the  host.  In  other 
words,  the  attack  of  most  plant  diseases 
depends  on  some  weak  point  in  the  cul- 
tural methods  which  has  weakened  the 
host  at  some  phase  in  its  life  history.  If 
we  accept  the  definition  of  disease  as  any 
serious  deviation  from  the  normal;  and 
admitting  as  we  do  that  proper  cultural 
conditions  are  necessary  to  maintain  the 
proper  balance  of  health  of  a  plant,  it  be- 
comes self  evident  that  a  discussion  of 
culture  requirements  goes  hand  in  hand 
with  any  discussion  on  plant  diseases.  To 
be  more  specific,  it  is  very  apparent  that 
the  man  who  understands  plant  life  in  all 
its  aspects  will  be  in  a  much  better  posi- 
tion to  also  cope  intelligently  with  any 
problem  of  disease  which  may  confront 
him  at  any  time.  Since  growers  as  a  rule 
must  be  their  own  plant  doctors  they  can- 
not be  provided  with  too  much  informa- 


PREFACE  xvii 

tion  on  cultural  requirements  of  the  par- 
ticular crop  with  which  they  are  concerned. 

Although  the  writer  had  considerable 
experience  in  growing  sweet  peas  in  the 
open  and  in  the  greenhouse,  he  felt  that 
this  ground  could  be  so  much  better  cov- 
ered by  eminent  specialists  such  as  Pro- 
fessor Beal  of  Cornell  University;  Mr. 
Cuthbertson,  Messrs.  Morse  and  Co.,  and 
all  the  others  who  are  here  quoted. 

It  may  perhaps  be  the  opinion  of  a  few 
that  a  book  on  plant  pathology  should  not 
include  a  discussion  on  insect  pests.  The 
writer,  however,  believes  that  in  a  specific 
work  of  this  nature  such  a  discussion  is  in- 
valuable. Insects  are  known  to  be  car- 
riers of  numerous  plant  diseases.  In  this 
work  it  would  be  rather  difficult  to  give  a 
complete  discussion  of  Mosaic,  or  in  fact 
of  any  of  the  other  sweet  pea  diseases  if 
we  were  to  leave  out  of  consideration  the 


xviii  PREFACE 

damage  caused  by  the  Pea  Aphis,  or  any 
other  of  the  insect  pests  here  described. 
The  writer  did  not  trust  to  his  own  knowl- 
edge of  Entomology.  Insect  specimens  in 
each  case  were  submitted  to  the  Depart- 
ment of  Entomology,  United  States  De- 
partment of  Agriculture  for  identification, 
and  there  due  credit  belongs. 

This  book  is  primarily  intended  to  be  a 
practical  treatise.  The  aim  cannot  be  at- 
tained if  our  study  is  to  be  deprived  of  its 
scientific  basis  and  its  scientific  value.  It 
is  hoped  this  double  character  of  the  work 
will  make  it  a  means  of  ready  reference 
for  both  growers  and  investigators. 

During  the  past  four  years  numerous 
letters  of  inquiry  have  been  received  by 
the  writer  from  sweet  pea  growers  rela- 
tive to  various  difficulties,  especially  those 
of  a  pathological  nature.  Although  hesi- 
tating to  make  hasty  suggestions,  we  could 


PREFACE  xix 

not  turn  a  deaf  ear  to  the  numerous  re- 
quests from  sweet  pea  growers  as  well  as 
from  technical  men  who  urged  the  prepara- 
tion of  a  book  of  this  nature.  The  writer 
seriously  solicits  suggestions  or  criticism 
of  this  work. 

Acknowledgments  are  due  to  Professor 
A.  C.  Beal,  Mr.  F.  G.  Cuthbertson,  and 
C.  C.  Morse  and  Co.  for  valuable  contri- 
butions on  the  culture  of  the  sweet  pea. 
To  Mrs.  D.  de  Sola  Pool  (nee  Miss  Tamar 
Hirchensohn),  previously  of  the  Faculty 
of  Hunter  College,  N.  Y.;  to  Dr.  Owen 
Sypherd  of  Delaware  College,  to  Dr.  C. 
H.  Farr  of  the  A.  and  M.  College  of 
Texas,  to  Dr.  M.  T.  Cook  of  Rutgers 
College  for  suggestions  in  reading  the 
manuscript.  To  the  Delaware  Experi- 
ment Station  for  figs.  7  to  21,  25  to  31,  38, 
42,  43,  and  45,  all  of  which  were  origin- 
ally taken  by  the  author.  All  the  other 


xx  PREFACE 

figures  have  been  accredited  in  their  proper 
places. 

Last  but  not  least,  acknowledgment  is 
due  my  wife,  Esther  Michla  Taubenhaus, 
by  whose  inspiration  this  work  was  made 
possible. 

J.  J.  TAUBENHAUS. 
College  Station,  Texas. 


CONTENTS 


INTRODUCTION 


CHAPTER 

I     HISTORY,  EVOLUTION,  CLASSIFICATION  AND 

CULTURE 9 

II    CULTURE  OF  THE  SWEET  PEA  FOR  SEEDS  .  60 

III  CULTURE  OF  SWEET  PEAS  UNDER  GLASS     .  74 

IV  DISEASES  OF  GREENHOUSE  SWEET  PEAS  .      .  90 
V    FIELD  DISEASES  OF  SWEET  PEAS  ....  135 

VI    DISEASES  NOT  YET  KNOWN  IN  AMERICA  .  149 

VII    INSECT  PESTS 152 

VIII    DISEASED   SEEDS 176 

IX    PHYSIOLOGICAL  DISEASES 181 

X    METHODS  OF  CONTROL 185 

XI    SPRAYING 204 

INDEX     ,                       227 


ILLUSTRATIONS 

A  Fine  House  of  Sweet  Peas  .      .      .     Frontispiece 

no.  PACK 

1  Method  of  Growing  Sweet  Peas  from  Seed  in 

England 39 

2  Trial  Grounds  of  C.  C.  Morse  &  Co.  .     .      .     70 

3  Field  of  Morse's  White  Spencer     ....     70 

4  Sweet  Peas  and  Carnations 89 

5  Root  Rot  caused  by  Rhizoctonia    ....     99 

6  Root  Rot  caused  by  Rhizoctonia   ....     99 

7  Hyphae  of  Rhizoctonia 102 

8  Culture  of  Sweet  Pea  Rhizoctonia  .      .      .      .102 

9  Culture  of  Fusarium  Lathy ri 102 

10  Chaetomium  Spirochaete 107 

11  Fusarium  Wilt 110 

12  Root  Rot  caused  by  Thielavia 113 

13  Root  Rot  caused  by  Thielavia 114 

14  Mycelium  of  Thielavia 116 

15  Powdery  Mildew 119 

16  Sclerotia  of  the  Sweet  Pea  Sclerotinia  .      .      .119 

17  Sclerotinia  Wilt  in  Seedlings 120 

18  Root  Knot  in  Sweet  Peas 124 

19  True  Legume  Root-Nodules 124 

20  Greenhouse  Thrips 131 

21  Red  Spider 132 

22  Triphleps  Insidiosus 133 

23  Anthracnose  Disease  on  the  Stem  .      .     .     .138 


ILLUSTRATIONS 

A  Fine  House  of  Sweet  Peas  .      .      .     Frontispiece 

NO.  PACK 

1  Method  of  Growing  Sweet  Peas  from  Seed  in 

England 39 

2  Trial  Grounds  of  C.  C.  Morse  &  Co.  .      .      .  70 

3  Field  of  Morse's  White  Spencer     ....  70 

4  Sweet  Peas  and  Carnations 89 

5  Root  Rot  caused  by  Rhizoctonia    ....  99 

6  Root  Rot  caused  by  Rhizoctonia   ....  99 

7  Hyphae  of  Rhizoctonia 102 

8  Culture  of  Sweet  Pea  Rhizoctonia  .      .      .      .102 

9  Culture  of  Fusarium  Lathyri 102 

10  Chaetomium  Spirochaete 107 

11  Fusarium  Wilt HO 

12  Root  Rot  caused  by  Thielavia 113 

13  Root  Rot  caused  by  Thielavia 114 

14  Mycelium  of  Thielavia 116 

15  Powdery  Mildew 119 

16  Sclerotia  of  the  Sweet  Pea  Sclerotinia  .      .      .119 

17  Sclerotinia  Wilt  in  Seedlings 120 

18  Root  Knot  in  Sweet  Peas 124 

19  True  Legume   Root-Nodules 124 

20  Greenhouse  Thrips 131 

21  Red  Spider 132 

22  Triphleps  Insidiosus 133 

23  Anthracnose  Disease  on  the  Stem  .      .      .      .138 


ILLUSTRATIONS 


TIG. 


24  Anthracnose  Disease  on  the  Leaf  ....   138 

25  Bitter  Rot  of  Apple 141 

26  Sweet  Pea  Mosaic 141 

27  Dwarfing  of  Plant  due  to  Mosaic  .      .      .      .142 

28  Plant  Outgrowing  Mosaic 144 

29  Culture  of  the  Streak  Organism      .      .      .      .148 

30  Sweet  Pea  Aphis  Parasitized 148 

31  Sweet  Pea  Aphis 153 

32  How  Aphids  Feed 156 

33  The  Convergent  Lady  Beetle 159 

34  Syrphid   Fly 160 

35  Green  Lace  Fly 162 

36  Aphidius  Testaceipes  Ovipositing    .      .      .      .163 

37  Aphelinus  Nigritus 166 

38  The  Striped  Blister  Beetle 170 

39  Variegated  Cut  Worm 171 

40  White  Grub  (May  Beetle) 174 

41  Anthracnose  Disease  on  Pods 177 

42  Fusarium  and  Botrytis  Fungi 178 

43  Auto-spray  No.  One 180 

44  The  Drugstore  Beetle l8b 

45  Soil  Infected  with  Fusarium  Lathyri   .      .      .   191 

46  Spraying  the  Sweet  Pea  Field 2 18 


CULTURE  OF  THE 
SWEET  PEA 

INTRODUCTION 

The  ancients  believed  that  diseases  in 
plants  were  induced  by  evil  spirits.  For 
instance,  the  rust  of  wheat  was  thought  by 
the  Romans  to  be  caused  by  the  evil  spirit 
Rubigo.  The  remedy  then  employed  was 
to  frighten  away  the  spirit  by  beating  with 
drums  of  various  kinds.  To-day,  some 
insist  that  all  plant  diseases  are  brought 
about  by  conditions  of  environment  such 
as  excessive  sunshine,  drought,  rain  or 
dew.  We  may  perhaps  justify  these  views 
when  we  consider  that  plants  in  their  mute 
way  are  unable  to  tell  of  their  ailments. 
The  keen  eye  and  the  close  observer,  how- 


2      CULTURE  OF  THE  SWEET  PEA 

ever,  have  singled  out  on  plants  parasitic 
organisms  whose  work  brings  about  devi- 
ations from  the  normal.  To-day  Plant 
Pathology  has  become  recognized  as  a 
definite  science.  There  is  hence  no  reason 
why  we  should  tolerate  certain  plant  dis- 
eases when  we  realize  the  vast  store  of 
scientific  knowledge  available.  Indeed  it 
is  highly  imperative  that  any  man  who  is 
engaged  in  the  growing  of  crops  should  be 
able  to  recognize  a  diseased  condition  in 
plants. 

Like  every  science,  Plant  Pathology  has 
made  slow  progress  in  its  beginning. 
Scholars  who  considered  it  from  a  purely 
speculative  or  philosophical  point  of  view 
only  were  interested  in  it  at  first.  It  was 
really  during  the  first  half  of  the  nine- 
teenth century  that  Plant  Pathology  built 
for  itself  a  solid  foundation,  and  gained 
a  place  among  the  leading  sciences.  It 


INTRODUCTION  3 

seems  that  it  was  very  difficult  for  schol- 
ars previous  to  the  nineteenth  century  to 
believe  otherwise  but  that  parasitic  fungi 
were  emanations  or  waste  products  of  the 
higher  plants.  It  was  DeBary  who  first 
established  definitely  that  healthy  plants 
may  be  attacked  and  penetrated  by  fungi. 
This  important  discovery  has  forever  dis- 
pelled doubt  as  to  the  parasitic  nature  of 
most  plant  diseases.  Nevertheless,  the 
economic  aspect  of  Plant  Pathology  could 
not  gain  much  impetus  as  long  as  growers 
were  content  to  lose  annually  from  five  to 
forty  per  cent,  of  their  crops.  It  required 
severe  epidemics  to  arouse  the  attention  of 
farmers  in  which  cases  they  turned  to  the 
scientist  for  help.  An  instance  of  this  is 
the  epidemic  of  late  blight  of  potatoes  in 
Ireland,  in  1845,  which  practically  re- 
sulted in  famine  and  great  hardship  to  the 
people.  Unfortunately,  there  were  no 


4      CULTURE  OF  THE  SWEET  PEA 

trained  Pathologists  at  that  time  to  cope 
with  the  situation.  A  similar  epidemic 
was  that  of  downy  mildew  of  grapes  in 
France,  in  1882.  France,  however,  met 
the  crisis  through  one  of  her  noble  sons, 
Professor  M.  Millardet,  then  of  the  Acad- 
emy of  Science  at  Bordeaux.  His  keen 
observations  and  studies  have  evolved  a 
remedy  for  the  grape  mildew.  Millardet 
was  in  fact  the  first  to  show  the  value  of 
copper  as  a  fungicide;  and  incidentally 
also  laid  the  foundation  to  modern  meth- 
ods of  spraying  and  of  disease  prevention 
in  general.  To-day  Plant  Pathologists 
are  everywhere  investigating  plant  dis- 
eases which  cause  serious  epidemics.  And 
they  are  going  farther,  for  the  diseases  of 
every  weed  is  important  and  will  aid  in 
the  solution  of  many  problems  regarding 
disease  in  vegetables,  fruits  and  crops. 
Although  nearly  every  Agricultural  Col- 


INTRODUCTION  5 

lege  or  University  in  the  United  States 
offers  courses  in  Plant  Pathology,  the  sup- 
ply of  trained  investigators  is  neverthe- 
less limited.  Since  every  Experiment  Sta- 
tion is  directly  supported  by  state  and 
federal  funds,  it  is  natural  that  every 
worker  is  more  or  less  impelled  to  inves- 
tigate diseases  of  plants  which  are  of 
greatest  economic  importance.  For  this 
reason  nearly  all  the  research  was  directed 
to  fruit,  cereal  and  forage  crops.  Flower 
pathology  is  as  yet  in  its  embryonic  stage. 
To-day  there  are  but  few  institutions  of 
learning  which  have  established  definite 
divisions  in  the  investigation  of  diseases 
of  ornamental  plants.  As  stated  in  the 
preface,  the  sweet  pea .  diseases  have 
received  scant  attention,  except  those 
worked  by  the  writer.  Even  in  this  case 
for  lack  of  funds  the  investigations  were 
brought  to  an  untimely  end.  The  little 


6      CULTURE  OF  THE  SWEET  PEA 

that  the  writer  was  able  to  contribute  was 
made  possible  through  the  moral  sup- 
port of  the  American  Sweet  Pea  Society; 
and  especially  by  money  donations  from 
the  various  seedsmen  and  other  lovers  of 
the  sweet  pea  in  the  United  States. 

It  is  believed  that  the  present  work  is 
fulfilling  an  urgent  need.  There  never 
was  a  time  when  ornamental  plants  were 
grown  commercially  on  a  larger  scale  than 
to-day.  In  fact  the  sweet  pea  itself  forms 
an  industry,  the  economic  importance  of 
which  cannot  be  overlooked.  It  is  within 
recent  memory  of  all  when  the  hollyhock 
occupied  the  place  of  honor  in  every  gar- 
den. In  every  flower  exhibit  in  this  coun- 
try or  abroad  it  was  king.  To-day  the 
hollyhock  is  only  mentioned  as  ancient  his- 
tory. Diseases  have  so  crippled  that  beau- 
tiful plant,  that  growers  out  of  sheer  dis- 
couragement have  ceased  raising  it.  Now 


INTRODUCTION  7 

it  is  found  occasionally  near  abandoned 
houses  or  in  neglected  back  yards.  The 
sweet  pea  is  undergoing  similar  critical 
periods.  In  England,  for  instance,  the 
' 'Streak"  already  constitutes  a  serious 
menace  to  profitable  sweet  pea  culture. 
The  same  conditions  are  beginning  to  pre- 
vail in  the  United  States,  and  several  per- 
plexing diseases  now  threaten  the  eco- 
nomic existence  of  one  of  the  most  delicate 
of  flowers. 


CHAPTER  I 

HISTORY,  EVOLUTION,  CLASSIFICATION  AND 
CULTURE  1 

AMONG  the  annual  flowers  none  excel 
the  sweet  pea  in  beauty,  usefulness,  fra- 
grance, and  range  of  color.  No  annual 
flower  is  more  popular.  If  the  rose  is  the 
Queen  of  Flowers,  the  sweet  pea  is  a  truly 
royal  princess  worthy  of  her  train.  This 
flower  has  long  been  grown  in  England 
and  America;  of  late  years  it  has  been 
gaining  in  favor  in  continental  Europe; 
and  it  is  also  extensively  grown  in  far-off 
Australia  and  Tasmania. 

The  sweet  pea  is  a  native  of  the  island 
of  Sicily.  It  was  first  mentioned  in  1695 

xBy  Professor  A.  C.  Beal  of  Cornell  University. 


10    CULTURE  OF  THE  SWEET  PEA 

by  an  Italian  monk  who  sent  seeds  to  Eng- 
land and  Holland.  In  England  sweet 
peas  were  cultivated  in  many  gardens. 
The  plant  is  one  of  the  species  of  Lathy- 
rus,  which  is  a  genus  of  Leguminosae.  Un- 
like other  species  of  this  genus,  the  sweet 
pea  has  fragrance,  and  Linnseus  gave  it  the 
name  of  odoratus.  Its  scientific  name, 
therefore,  is  Lathyrus  odoratus.  The 
color  of  the  original  sweet  pea  was  purple 
in  the  standard,  and  sky-blue  in  the  wings. 
During  the  first  one  hundred  years  of 
its  history  there  was  little  improvement 
in  the  sweet  pea.  A  variety  with  white 
flowers  and  another  with  pink  and  white 
flowers  were  developed.  The  first  half  of 
its  second  century  of  cultivation  was  sig- 
nalized by  the  development  of  several  va- 
rieties, so  that  in  1860  there  were  nine 
known  varieties.  About  this  time  seeds- 
men began  to  take  greater  interest  in 


HISTORY  AND  EVOLUTION         11 

sweet  peas;  but  more  varieties  came  in 
slowly.  Every  flower,  however,  that  has 
won  popular  favor  has  had  at  least  one 
great  genius  to  develop  it.  The  greatest 
genius  in  sweet  peas  was  Henry  Eckford, 
who  commenced  crossing  the  best  obtain- 
able varieties  about  1878,  and  began  to 
sell  new  varieties  in  1883.  Steadily  he 
kept  at  work  until,  at  his  death  in  1905, 
although  the  number  had  increased  to 
more  than  three  hundred,  he  was  to  be 
credited  with  originating  most  of  the  lead- 
ing varieties.  About  1890,  the  American 
sweet  pea  growers  began  to  appreciate  the 
beautiful  varieties  Mr.  Eckford  was  send- 
ing out  and  there  was  a  wave  of  popularity 
for  the  flower.  The  discovery  that  Cali- 
fornia had  a  favorable  climate  for  the  pro- 
duction of  sweet  •  pea  seed  enabled  the 
seedsmen  to  supply  the  greatly  increased 
demand.  This  development  has  con- 


12    CULTURE  OF  THE  SWEET  PEA 

tinued  until  the  larger  part  of  the  world's 
supply  now  comes  from  California. 

Meanwhile  the  variety  Blanche  Ferry 
was  discovered  growing  in  a  garden  in 
New  York  State  and  was  put  on  the  mar- 
ket in  1889.  From  this  was  developed  the 
varieties  Early  Blanche  Ferry,  Earliest  of 
All,  Earliest  White,  and  the  whole  race  of 
winter-flowering  sweet  peas.  The  Ameri- 
can originators  have  given  us  many  good 
striped  varieties,  such  as  America,  Aurora, 
etc.,  and  also  such  blues  as  Navy  Blue  and 
Flora  Norton.  Other  notable  varieties 
are  Helen  Pierce,  Dainty,  Janet  Scott, 
Emily  Henderson,  Phenomenal,  Stella 
Morse,  Admiration,  Shasta,  and  White 
Wonder.  The  dwarf  or  Cupid  sweet  peas 
originated  in  California  and  were  offered 
in  1896. 

During  the  closing  years  of  Mr.  Eck- 
ford's  busy  life,  at  a  time  when  some  grow- 


HISTORY  AND  EVOLUTION         13 

ers  thought  that  the  limit  of  development 
in  sweet  peas  had  almost  been  reached,  a 
new  type  of  sweet  peas  appeared.  This 
was  the  waved  or  Spencer  type.  The  first 
variety,  Countess  Spencer,  sent  out  by  Mr. 
Cole  (the  originator)  in  1904,  was  at  once 
very  popular,  and  since  that  time  there 
has  been  an  extraordinary  interest  in  sweet 
peas  on  both  sides  of  the  Atlantic.  How- 
ever, the  greatest  interest  has  been  in  Eng- 
land, where  a  great  many  persons  are  in- 
terested in  originating  new  varieties  and 
a  large  number  are  placed  on  the  market 
each  year.  Numerous  exhibitions  are 
held,  and  the  National  Sweet  Pea  Society 
has  over  one  thousand  members. 

Although  the  interest  in  sweet  peas  in 
America  is  not  so  intense,  yet  this  flower 
is  seen  in  almost  every  home  garden, 
where  it  is  cherished  for  its  special 
beauty. 


14    CULTURE  OF  THE  SWEET  PEA 

The  sweet  pea  may  be  classified  accord- 
ing to  the  habit  of  the  plant  into 
i  Garden  varieties 


Climbing  s™. 

[Winter-flowering 

TN       £  [Cupids 

Dwarf  -A-,  \       •    •      /          i     i      v 
[Bush  varieties  (now  obsolete) 

It  is  important  to  remember  that  the  win- 
ter-flowering varieties  are  absolutely  dis- 
tinct from  the  garden  varieties  in  their 
habit  of  growth.  The  Cupids  are  occa- 
sionally grown  because  of  their  novelty. 

Sweet  peas  are  usually  classified  accord- 
ing to  the  form  of  the  flower.  The  earliest 
known  varieties  of  the  sweet  pea  had  flow- 
ers in  which  the  standards  were  reflexed 
and  deeply  notched  at  the  apex.  The  ef- 
fort of  Mr.  Eckford  and  others  was  to 
eliminate  the  notch  and  give  the  standard 
greater  substance  so  that  it  could  hold  it- 
self erect.  This  brought  about  the  open 
form  which  often  retained  something  of 


HISTORY  AND  EVOLUTION         15 

the  apical  notch.  Then  came  the  hooded 
form,  in  which  the  edges  of  the  standards 
are  rolled  forward.  There  are  various  de- 
grees of  hooding  in  different  varieties. 
Extreme  hoodings  were  at  one  time  recog- 
nized under  the  name  of  snapdragon  va- 
rieties, which  were  never  more  than  a  pass- 
ing novelty.  Finally,  there  is  the  waved 
form  in  which  the  edges  of  the  standards 
and  often  the  wings  are  beautifully 
waved.  This  is  the  most  handsome  form 
of  sweet  pea  flower  (the  flowers  are  larger 
and  have  longer  stems) ,  and  it  is  probable 
that  the  other  forms  will  pass  away.  The 
older  types,  however,  seed  more  freely,  and 
therefore  it  has  been  possible  to  produce 
seed  more  cheaply.  However,  any  one 
who  has  grown  the  waved  or  Spencer  va- 
rieties will  not  again  take  up  the  culture  of 
the  old  varieties,  and  therefore  in  the 
course  of  time  the  latter  are  doomed. 


16    CULTURE  OF  THE  SWEET  PEA 

The    following    is    a    classification    of 
sweet  peas  according  to  form : 


Garden  type 

Open  form 
Hooded  form 
Waved  form 

Winter-  flowering 
type 
Open  form 
Hooded  form 
Waved  form 

Dwarf  Type 
(Cupid) 
Open  form 
Hooded  form 

Sweet  peas  are  classified  also  according 
to  color.  The  English  Sweet  Pea  Society 
recognizes  thirty-two  color  classes  as  fol- 
lows: Bicolor;  Blue;  Blush;  Carmine; 
Cerise;  Cream,  Buff,  and  Ivory;  Cream- 
pink  (Pale) ;  Cream-pink  (Deep) ;  Crim- 
son; Fancy;  Lavender;  Lilac;  Magenta; 
Marbled  and  Watered;  Maroon;  Maroon 
Purple;  Maroon  Red;  Mauve  (Dark) ; 
Mauve  (Pale) ;  Orange-pink;  Orange 
Scarlet;  Picotee  Edged  (Cream  Ground) ; 
Picotee  Edged  (White  Ground) ;  Pink 
(Deep);  Pink  (Pale);  Rose;  Salmon 
Shades;  Scarlet;  Striped  and  Flaked 


HISTORY  AND  EVOLUTION         17 

(Purple  and  Blue)  ;  Striped  and  Flaked 
(Chocolate  on  Gray  Ground)  ;  Striped  and 
Flaked  (Red  and  Rose) ;  White. 

When  one  compares  this  with  the  fol- 
lowing classification  used  in  a  prominent 
seedsman's  catalogue  only  fifteen  years 
ago,  one  can  appreciate  the  marvelous  de- 
velopment in  the  sweet  pea.  This  cata- 
logue grouped  all  varieties  under  White, 
Cream,  Light  Yellow,  Light  Blush, 
Light  Pink,  Deep  Pink,  Rose,  Red  and 
Scarlet,  Shades  of  Orange  and  Salmon, 
Pink  and  White,  Blue  and  White,  Claret 
and  Maroon,  Striped  and  Variegated, 
Lavender  and  Light  Blue,  and  Blue  and 
Purple. 

VARIETIES 

Catalogues  usually  classify  sweet  peas 
according  to  color  with  a  separate  list  of 
the  winter-flowering  varieties. 

More    than    twelve   hundred   varieties 


i8    CULTURE  OF  THE  SWEET  PEA 

of  sweet  peas  have  been  introduced. 
Many  varieties  have  passed  into  oblivion, 
but  there  are  large  numbers  in  the 
trade  and  every  season  witnesses  a  con- 
siderable number  of  aspirants  for  public 
favor.  The  following  list  is  the  result  of 
testing  hundreds  of  varieties  during  the 
last  few  years.  It  is  a  matter  of  personal 
taste  whether  some  of  the  colors,  as  repre- 
sented by  the  color  sections,  are  desirable 
for  any  particular  garden.  The  classifica- 
tion will  enable  any  one  to  select  those  col- 
ors and  varieties  suited  to  individual 
tastes. 

WAVED    VARIETIES 

Bicolor — Mrs.  Cuthbertson,  Colleen 

Blue — Margaret  Madison,  Flora  Norton  Spencer, 

Blue  Jacket 
Blush — Lady    Evelyn    Eyre,    Princess    Victoria, 

Florence  Morse  Spencer 
Carmine — John  Ingman 
Cerise — Chrissie  Unwin 


HISTORY  AND  EVOLUTION         19 

Cream,  Buff,  and  Ivory — Primrose  Spencer,  Isabel 
Malcolm,  Primrose  Beauty,  Lady  Knox, 
Queen  Victoria  Spencer. 

Cream-pink  (Deep) — Mrs.  Gibbs  Box,  Constance 
Oliver 

Cream-pink  (Pale) — Mrs.  Routzahn,  Lady  Mil- 
ler, Mrs.  Hugh  Dickson 

Crimson — King  Edward  Spencer 

Fancy — Afterglow 

Lavender — Florence  Nightingale 

Magenta — Menie  Christie 

Marbled — May  Campbell 

Maroon — Nubian,  King  Manuel 

Maroon-purple — Arthur  Green 

Maroon-red — Brunette,  Red  Chief 

Mauve  (Dark) — Tennant  Spencer 

Mauve  (Pale) — Mrs.  Heslington,  Mauve  Queen 

Orange-pink — Edrom  Beauty,  Carene,  Helen 
Lewis 

Orange-scarlet — Thomas  Stevenson 

Picotee  edged  (Cream  ground) — Evelyn  Hemus, 
Mrs.  C.  W.  Breadmore 

Picotee  edged  (White  ground) — Dainty  Spencer, 
Elsie  Herbert,  Martha  Washington 

Pink  (Deep) — Hercules,  Countess  Spencer 


20     CULTURE  OF  THE  SWEET  PEA 

Pink  (Pale)— Elfrida  Pearson 

Rose — Marie  Corel  li,  Rosabelle 

Salmon  Shades — Stirling  Stent,  Melba,  Barbara 

Scarlet — Bobbie's  Scarlet,  Scarlet  Emperor,  Red 

Star 
Striped  and  Flaked  (Chocolate  on  gray  ground) 

— Senator  Spencer 

Striped  and  Flaked  (Purple  and  blue) — Loyalty 
Striped  and  Flaked   (Red  and  rose) — America 

Spencer,  Aurora  Spencer,  Mrs.  W.  J.  Unwin 
White — White  Spencer,  Nora  Unwin 

VARIETIES    OF    OPEN    AND    HOODED    FORMS 

Bicolor — Blanche  Ferry,  Jeannie  Gordon 

Blue— Brilliant  Blue,  Navy  Blue 

Blue  (Light) — Flora  Norton 

Blush — Modesty 

Cerise — Coccinea 

Cream,  Buff  and  Ivory — Zarina,  The  Honorable 

Mrs.  E.  Kenyon,  Queen  Victoria 
Crimson — King  Edward  VII 
Lavender — Lady  Grizel  Hamilton 
Marbled — Helen  Pierce 
Maroon — Black  Knight,  Othello 


HISTORY  AND  EVOLUTION        21 

Mauve — Admiration,  Mrs.  Walter  Wright, 
Dorothy  Tennant 

Orange  Shades — Henry  Eckford,  Miss  Wilmott 

Picotee  edged — Dainty,  Lottie  Eckford,  Phenom- 
enal 

Pink — Prima  Donna,  Lovely,  Katherine  Tracy, 
Janet  Scott 

Rose  and  Carmine — Lord  Roseberry 

Scarlet — Queen  Alexandra 

Striped  and  Flaked  (Chocolate  on  gray  ground) 
— Senator 

Striped  and  Flaked  (Purple  and  blue) — Princess 
of  Wales,  Hester 

Striped  and  Flaked  (Red  and  rose) — America, 
Aurora,  Romona 

White — Dorothy  Eckford,  Shasta,  Emily  Hender- 
son, White  Wonder 

EARLY-FLOWERING    VARIETIES 

Bicolor — Earliest  of  All 

Blue — Le  Marquis 

Lavender — Mrs.  Alexander  Wallace 

Primrose — Earliest  Sunbeams 

Salmon-pink — Mrs.  William  Sim 


22    CULTURE  OF  THE  SWEET  PEA 

MARKET    VARIETIES 

Open  and  hooded  varieties — Dorothy  Eckford, 
King  Edward  VII,  Brilliant  Blue,  Lady  Grizel 
Hamilton,  Prima  Donna,  Blanche  Ferry 

Waved  varieties — Countess  Spencer,  Nora  Un- 
win,  Asta  Ohn,  King  Edward  Spencer 

CULTURAL  REQUIREMENTS 
SITE.  Sweet  peas  should  be  planted 
where  they  can  get  the  maximum  amount 
of  sunlight,  and  the  rows  should  run  north 
and  south.  A  free  circulation  of  air  is 
beneficial,  but  the  best  site  is  one  which  is 
not  swept  by  strong  winds,  which  break 
the  plants  from  their  supports  and  injure 
the  stems  of  the  plants.  Any  injury  to  the 
stem  of  the  plant  invariably  results  in 
smaller  flowers  and  shorter  flower  stems. 

SOIL.  Any  garden  soil  is  suitable  for 
sweet  peas,  provided  it  is  sufficiently 
drained  so  that  in  periods  of  excessive 
rains  the  water  will  not  lie  upon  the  sur- 


HISTORY  AND  EVOLUTION        23 

face  about  plants,  and  thus  cause  them  to 
become  yellow  or  to  decay  at  the  roots. 
Soil  suitable  for  growing  vegetables  usu- 
ally gives  good  results,  but  extra  care  in 
the  selection  and  preparation  of  the  soil 
will  be  repaid  in  larger  flowers,  longer 
stems,  better  colors,  and  a  longer  blooming 
period. 

PREPARATION.  The  sweet  pea  is  a  deep- 
rooting  plant,  and  in  order  to  provide 
suitable  conditions  so  that  the  effects  of 
drought  will  be  overcome,  the  preparation 
of  the  soil  must  be  deep  and  thorough. 
Whatever  the  nature  of  the  soil,  unques- 
tionably the  best  preparation  can  be  made 
by  trenching  the  soil  in  the  autumn.  This 
means  turning  the  soil  to  a  depth  ranging 
from  18  inches  to  as  much  as  three  feet. 
In  America  this  method  is  usually  found 
too  expensive,  and  instead  a  trench  15  to 
18  inches  wide  along  the  line  of  the  rows 


24    CULTURE  OF  THE  SWEET  PEA 

is  used.  The  soil  is  removed  and  replaced 
with  prepared  soil  made  by  composting 
sod  from  an  old  pasture  with  manure.  If 
this  method  cannot  be  followed,  the  top 
soil,  to  the  depth  of  one  foot,  can  be  thrown 
out  on  one  side  of  the  trench  and  the  lower 
soil  broken  up  as  deep  as  possible  with  a 
pick.  If  a  good  application  of  stable  ma- 
nure can  be  mixed  with  the  subsoil  the  re- 
sults are  better.  Often  a  layer  of  leaves 
or  coarse  manure  placed  in  the  bottom  of 
the  deep  trench  serves  to  promote  drain- 
age. In  all  cases  the  trenches  should  be 
from  18  inches  to  two  feet  deep,  and  it  is 
a  good  plan  to  work  in  all  the  manure  pos- 
sible. It  does  not  matter  in  the  fall-prepa- 
ration of  the  soil  if  the  manure  is  fresh, 
but  of  course  strawy  manure  will  not  do 
except  in  the  bottom  of  the  trench.  A 
good  application  of  lime  should  be  made 
while  preparing  the  soil  in  the  autumn. 


HISTORY  AND  EVOLUTION        25 

Many  soils  that  have  been  cultivated  for 
a  long  time  are  acid,  and  therefore  not 
adapted  for  growing  leguminous  plants 
such  as  clover  or  sweet  peas  even  though 
the  soil  may  be  fertile.  The  lime  corrects 
this  condition,  and  also  releases  plant  food 
which  otherwise  would  not  soon  become 
available.  Clay  soils  are  made  more  open 
and  porous  by  the  action  of  lime. 

PLANTING 

THE  SEED.  Some  primrose  and  white- 
flowered  varieties  have  white  or  light-col- 
ored seeds,  and  some  have  black  seeds. 
The  white  seeds  often  rot  in  the  soil,  espe- 
cially if  they  are  planted  early  when  the 
soil  is  cold,  or  because  their  germinating 
power  has  been  impaired;  also  they  fre- 
quently split  in  the  pod  before  harvesting 
and  in  this  condition  are  likely  soon  to  lose 
their  vitality.  For  the  foregoing  reasons 


26    CULTURE  OF  THE  SWEET  PEA 

it  is  advisable  to  sow  seeds  of  this  color 
close  together  and  not  so  deep  as  the  black- 
seeded  varieties. 

In  some  seasons,  sweet  pea  seeds  are 
slow  in  germinating.  It  is  well  to  exam- 
ine such  seeds  in  order  to  ascertain  their 
condition.  If  the  seeds  are  found  dor- 
mant but  still  fresh  and  plump,  the  seed- 
coats  should  be  cut  with  a  sharp  knife  and 
replanted;  they  will  then  germinate  well. 
This  difficulty  is  not  confined  to  the  sweet 
pea;  some  of  the  other  species  of  Lathyrus 
behave  similarly.  The  trouble  usually 
follows  a  very  hot  dry  season,  when  the 
seed  becomes  so  excessively  ripened  as  to 
render  the  seed-coat  impervious  to  water. 
Sometimes,  in  order  to  expedite  germina- 
tion, the  seeds  are  soaked;  a  better  method 
for  the  amateur  is  that  recommended  by 
Mr.  Hutchins.  He  places  the  seed  pack- 
ets in  moist  earth  for  seven  or  eight  days. 


HISTORY  AND  EVOLUTION        27 

He  then  takes  them  out  and  examines 
them;  the  swollen  seeds  are  planted,  and 
the  others  cut  with  a  knife. 

FALL  PLANTING.  Often  the  finest  as 
well  as  the  earlier  flowers  are  secured  from 
plants  the  seed  of  which  was  sown  in  the 
fall.  South  of  the  latitude  of  New  York 
City  this  time  of  sowing  can  be  recom- 
mended. North  of  this  line  this  method 
cannot  always  be  depended  upon  unless  a 
sandy,  well-drained  soil  is  chosen.  If  the 
water  does  not  lie  upon  the  ground  in  win- 
ter, and  particularly  if  there  is  little  or  no 
freezing  and  thawing,  it  is  advisable  to 
give  this  method  of  planting  a  trial.  The 
same  preparation  of  the  soil  is  made  as  de- 
scribed above,  but  care  must  be  taken  to 
firm  the  soil  so  that  it  does  not  settle.  The 
trench  or  furrow  should  be  filled  so  as  to 
allow  for  a  slight  settling  of  the  soil,  thus 
producing  a  slightly  crowning  ridge.  In 


28    CULTURE  OF  THE  SWEET  PEA 

this  ridge  a  little  furrow,  two  inches  deep, 
should  be  made ;  or,  if  preferred,  two  small 
furrows  of  equal  depth  six  inches  apart 
may  be  made.  The  seeds  should  be  sown 
one  or  two  inches  apart  in  these  furrows 
and  covered  so  that  the  surface  is  slightly 
ridged  for  drainage.  The  most  important 
point  in  fall  planting  of  sweet  peas  is  to 
plant  so  late  that  the  plants  do  not  appear 
above  the  surface  before  freezing.  In  the 
Northern  states,  if  the  plants  appear  above 
the  surface  of  the  ground,  they  will  be 
killed  by  the  winter.  Seed  that  have  only 
"sprouted,"  however,  will  not  be  harmed. 
In  central  New  York  it  has  been  found 
that  after  November  10  is  the  best  time  to 
sow,  but,  of  course,  this  varies  with  the 
season. 

After  the  ground  freezes,  a  mulch  of 
manure  should  be  placed  over  the  row,  and 
if  the  snow  remains  upon  the  ground  all 


HISTORY  AND  EVOLUTION        29 

the  winter  the  conditions  are  most  favor- 
able. The  approach  of  bright  weather  in 
spring  is  the  time  to  examine  your  sweet 
peas  to  see  whether  they  are  growing. 
Often  the  manure  mulch  keeps  the  soil 
soggy  and  cold  when  the  bare  soil  is  be- 
coming dry  and  warm.  In  such  cases  re- 
move a  portion  or  all  of  the  mulch,  leav- 
ing it  between  the  rows  or  near  at  hand, 
so  that  if  there  should  be  a  cold  wave  it 
can  be  used  to  cover  the  plants.  The 
plants  from  fall-sown  seed  get  an  earlier 
start  than  it  is  possible  to  secure  by  sow- 
ing in  the  spring.  The  seed  of  standard 
varieties  of  sweet  peas  is  so  cheap  that  the 
fall-planting  of  sweet  peas  is  an  effort  well 
worth  while. 

SPRING  PLANTING.  As  soon  as  the  frost 
is  out  of  the  ground  and  the  soil  is  in  work- 
able condition  in  the  spring,  a  heavy  ap- 
plication of  superphosphate  of  lime  should 


30    CULTURE  OF  THE  SWEET  PEA 

be  made  and  raked  in.  Care  should  be 
exercised  not  to  get  the  soil  too  loose,  and 
for  this  reason  it  is  best  to  confine  all  stir- 
ring of  the  soil  to  smoothing  the  surface. 
Especially  is  this  true  with  light  soils, 
which,  if  stirred  deeply  in  the  spring,  must 
be  well  firmed.  Heavy  soils  that  are 
likely  to  bake  may  be  improved  by  work- 
ing in  a  light  dressing  of  old,  thoroughly 
rotted  manure. 

Sweet  peas  should  be  sown  as  early  in 
the  spring  as  the  soil  is  dry  enough  to 
work,  even  though  it  is  probable  that 
heavy  frosts  will  follow.  The  writer 
thinks  that  one  reason  why  even  the  most 
inexperienced  amateur  usually  has  such 
good  average  results  with  sweet  peas,  is 
that  he  gets  his  annual  "violent  attack  of 
gardening  fever"  in  early  spring,  and  he 
begins  his  operations  at  just  the  right  time 
for  sweet  peas  to  go  into  the  ground. 


HISTORY  AND  EVOLUTION        31 

An  essential  requirement  in  growing 
sweet  peas  is  to  plant  early,  while  the 
atmospheric  conditions  are  such  as  to  pre- 
vent top  growth  before  the  plant  has 
started  a  vigorous  root  development.  The 
result  is  that,  when  warmer  weather  comes, 
the  top  grows  strong  and  heavy,  the  plant 
branches  out,  and  throughout  the  season 
this  increased  vigor  is  evident.  Experi- 
ments made  by  sowing  seeds  every  ten  days 
from  the  earliest  practicable  date  until  the 
end  of  May  indicate  that  early  planting  is 
desirable. 

DEPTH.  If  the  preparation  of  the  soil 
has  been  made  in  the  fall,  it  is  advisable 
to  smooth  the  surface  of  the  trench  and 
plant  in  this.  When  the  preparation  has 
been  made  in  the  spring  the  soil  must  not 
be  left  too  loose — a  condition  that  may 
easily  occur  if  a  deep  trench  is  made  and 
only  loosely  filled  with  soil  and  manure. 


32    CULTURE  OF  THE  SWEET  PEA 

One  method  recommended  is  to  hollow 
out  a  broad  trench,  twenty-four  to  thirty 
inches  wide  and  two  inches  deep,  and  then 
sow  the  seed  one  inch  deep  in  single  or 
double  rows.  The  trench  should  be  kept 
open  for  six  weeks  in  order  to  retain  the 
water.  This  system  is  very  good  in  a  gar- 
den where  all  cultivation  is  given  by  hand ; 
but  where  many  rows  are  grown  and  cul- 
tivation is  done  with  a  horse  and  culti- 
vator, it  is  manifestly  impossible  to  make 
or  to  maintain  such  a  trench.  Further- 
more, when  horse  cultivation  is  used  there 
is  difficulty  in  keeping  the  young  plants, 
if  planted  below  the  surface,  from  being 
covered  during  the  early  cultivations. 
Therefore,  planting  on  the  level  is  neces- 
sary in  field  culture.  It  is  advisable,  how- 
ever, in  garden  culture,  to  plant  so  that 
when  covered  the  row  will  be  two  inches 
below  the  ordinary  level. 


HISTORY  AND  EVOLUTION        33 

The  seed  may  be  sown  in  single  or  dou- 
ble drills  as  described  under  fall-planting. 
It  is  advisable  to  sow  the  seeds  one  or  two 
inches  apart;  if  it  is  suspected  that  a  good 
germination  will  not  result,  more  seed 
should  be  sown. 

THINNING.  Many  persons  do  not  thin 
their  plants,  and  in  many  cases  the  reason 
that  poor  flowers  are  obtained  is  because 
of  overcrowding.  On  the  other  hand,  the 
practice  of  English  gFowers  of  thinning 
the  plants  so  that  they  stand  several  inches 
apart,  will  not  bring  successful  results  in 
our  climate.  It  is  difficult  to  give  instruc- 
tions that  will  apply  everywhere;  but  un- 
der conditions  in  New  York  state  thinning 
the  plants  so  that  they  are  from  four  to 
six  inches  apart  has  given  the  best  results. 

American  sweet-pea  growers  almost  in- 
variably plant  sweet  peas  in  rows,  but  gar- 
den lovers  are  advised  to  try  the  method 


34    CULTURE  OF  THE  SWEET  PEA 

of  planting  sweet  peas  in  small  circles  or 
even  in  clumps.  Grown  in  this  manner, 
sweet  peas  may  be  effectively  used  in  the 
flower  garden  and  in  borders.  The  prepa- 
ration of  the  soil  is  similar  to  that  for  the 
other  method  of  planting. 

SOWING  IN  POTS  FOR  OUTDOOR  BLOOM. 
Many  English  growers  practice  sowing  in 
pots  under  glass,  hardening  the  plants  in 
frames,  and  planting  out.  From  his  own 
experience,  the  writer  is  inclined  to  look 
on  this  method  with  favor,  especially  in 
growing  high-priced  novelties  or  varieties 
for  exhibition. 

In  the  greenhouse  the  seed  may  be  sown 
in  February  or  March.  Usually  it  is  best 
to  sow  about  six  weeks  before  one  expects 
to  plant  in  the  open  ground.  The  seeds 
are  sown  in  three  and  one-half  or  four- 
inch  pots,  using  a  good  compost  of  rotted 
sod,  well-decayed  manure  or  leaf  mold, 


HISTORY  AND  EVOLUTION        35 

and  sand.  A  little  of  the  rougher  portion 
of  the  turf  should  be  placed  in  the  bottom 
of  the  pot  to  insure  drainage.  Fill  the 
pots  firmly  to  within  one  and  one-half 
inches  of  the  top  and  sow  four  seeds  at 
equal  distances  apart,  and  cover  them  with 
an  inch  of  soil.  Label  each  variety  care- 
fully as  the  seed  is  sown.  The  pots  are 
then  placed  in  a  cool  greenhouse ;  and  after 
germination,  if  the  weather  is  favorable, 
transferred  to  cold-frames  to  harden  the 
plants.  The  pots  may  be  placed  in  cold- 
frames  immediately  after  sowing,  but  they 
cannot  be  sown  as  early  as  in  the  green- 
house. The  seeds  of  some  of  the  new  va- 
rieties appear  to  have  thick  seed-coats,  and 
therefore  do  not  germinate  readily.  Such 
seeds  should  be  clipped  with  a  knife  so  that 
the  moisture  can  penetrate  the  seed-coats. 
After  the  plants  appear  the  pots  should  be 
kept  near  the  glass  so  that  the  plants  will 


36    CULTURE  OF  THE  SWEET  PEA 

be  dwarf  and  sturdy.  Care  must  be  em- 
ployed in  watering  so  that  the  soil  does  not 
become  sour;  and  watering  the  pots  in 
frames  should  be  done  in  clear  weather  so 
that  the  plants  will  dry  off  before  night, 
for  if  the  night  is  frosty  the  plants  may 
suffer.  In  severe  weather  the  frames  must 
be  protected  by  mats  and  banked  up  with 
manure.  The  frames  must  be  kept  well 
ventilated,  and  as  warm  weather  advances 
the  sash  should  be  entirely  removed  during 
the  day.  Proper  handling  during  plant- 
ing out  will  insure  success. 

If  the  plants  begin  to  form  tendrils,  a 
few  twigs  should  be  inserted  to  support 
the  plants.  Results  of  the  neglect  of  this 
important  requirement  will  be  apparent 
later  in  the  season.  Except  when  grown 
for  market  purposes,  for  which  earliness 
is  an  important  consideration,  it  is  advis- 
able for  the  amateur  to  delay  the  sowing 


HISTORY  AND  EVOLUTION        37 

so  that  the  plants  in  pots  do  not  become 
tall  enough  to  require  much  support.  The 
usual  practice  is  to  plant  these  pot-clumps 
twelve  to  eighteen  inches  apart  in  the  row. 
The  entire  potful  is  planted  without  dis- 
turbing the  twigs  supporting  the  plants. 
It  is  better  to  pick  out  the  crock  from  the 
ball  since  it  loosens  the  tips  of  the  roots 
which,  when  planted,  are  encouraged  to 
strike  down  into  the  soil.  Sometimes,  the 
roots  are  long,  and  therefore  are  wound 
around  the  ball  of  earth  in  the  pot;  if  they 
are  not  loosened,  they  may  continue  to 
grow  in  the  same  manner,  thus  not  estab- 
lishing connection  with  the  soil  prepared 
for  the  plants.  It  is  essential  to  keep  the 
roots  growing  down  into  the  cooler, 
moister  soil.  No  difficulty  will  be  experi- 
enced in  planting  sweet  peas  from  pots, 
provided  they  have  been  given  a  good 
watering  the  day  before  planting,  which 


38    CULTURE  OF  THE  SWEET  PEA 

will  aid  in  keeping  the  ball  of  earth  entire 
when  the  plants  are  knocked  out  of  the 
pots.  If  the  soil  is  dry  when  the  planting 
is  done,  it  will  often  be  advisable  to  water 
the  plants  when  they  are  set.  Under  nor- 
mal conditions,  however,  this  practice  is 
not  advised. 

THE  CORDON  SYSTEM/  After  trans- 
planting, pinch  off  the  tip  or  growing 
point  of  the  plant  and  allow  only  two  lat- 
erals to  develop.  Pinch  off  all  others  and 
thereafter  allow  only  two  shoots  on  each 
plant.  If  the  ground  has  previously  been 
well  firmed  down,  the  plants  will  be  sturdy 
and  short  jointed,  producing  an  abundance 
of  blossoms.  For  the  cordon  system  the 
plants  should  be  trained  up  on  tall  sticks 
about  ten  feet  high,  which  have  been  se- 
curely fastened  at  their  upper  end  to  a 
stretched  wire.  A  good  practice  is  to  have 

1  By  Frank  G.  Cuthbertson,  Sweet  Pea  Specialist. 


Fig.  i.— Method  of  growing  Sweet  Peas  for  seed  in 
England.     The  vines  are  trained  on  tree  boughs, 

and  the  pods  gathered  by  hand. 
View  at  Dobbie  and  Co.'s  seed  farm,  England. 


HISTORY  AND  EVOLUTION        39 

a  double  row  of  plants  about  ten  inches 
apart  and  a  double  row  of  stakes  or  sup- 
ports. If  stakes  cannot  be  had,  strings 
may  be  stretched  from  a  line  of  wire  ten 
feet  high  down  to  the  plants  and  pegged 
down.  The  shoots  will  have  to  be  tied  to 
the  stakes  or  strings  as  fast  as  they  grow, 
thus  preventing  the  breaking  of  stems  and 
blossoms.  The  tendrils  should  also  be  cut 
off,  as  well  as  all  laterals  as  they  appear. 

By  following  the  cordon  system  the 
leaves  will  be  very  large  and  the  flowers 
will  have  standards  of  one  and  one-half 
or  two  inches  across. 

SUPPORTS.  Among  English  sweet  pea 
growers  there  is  considerable  unanimity 
of  opinion  that  sticks  form  the  best  sup- 
port for  sweet  peas  (fig.  i ) .  The  replies 
of  fifty-two  leading  experts,  published  in 
the  Sweet  Pea  Annual  for  1907,  show  that 
forty- three  growers  favor  sticks  (gener- 


40    CULTURE  OF  THE  SWEET  PEA 

ally  hazel  sticks) ,  five  favor  wire  netting, 
two  favor  either  sticks  or  wire  netting  (the 
netting  if  new  to  be  painted) ,  one  prefers 
sticks  and  string,  and  the  remaining  one,  a 
correspondent  from  British  Columbia,  uses 
telephone  wire  and  string. 

In  this  country,  where  good  twiggy 
boughs  can  be  obtained  such  boughs  un- 
questionably form  the  best  support  to  use 
since  they  are  the  most  natural.  In  many 
places  birch  boughs  can  be  obtained  in 
lengths  of  twelve  to  fourteen  feet.  These 
may  be  prepared  in  the  lengths  desired. 

The  height  of  the  support  must  be  de- 
termined by  the  grower.  If  the  soil  has 
been  prepared  properly  and  the  plants 
look  strong,  and  if  the  grower  waters  the 
plants  properly  and  gives  them  every  care, 
then  the  support  should  be  six  feet  high. 
If  the  soil  is  only  moderately  fertile  or 
has  not  been  properly  prepared,  or  if  the 


HISTORY  AND  EVOLUTION        41 

grower  does  not  intend  to  keep  all  seed- 
pods  picked  off  or  cannot  water  the  plants 
in  order  to  overcome  drought,  the  support 
should  be  kept  down  to  four  feet.  The 
variety  has  something  to  do  with  the 
height  of  the  support,  whatever  the  care 
bestowed,  some  varieties  being  naturally 
dwarfs. 

The  sticks  should  be  cut  in  late  winter 
or  very  early  spring  so  that  they  are 
rather  green  and  tough  enough  to  bear  the 
load  until  the  end  of  the  season.  They 
should  be  inserted  in  the  soil  at  least  a  foot, 
because  when  they  are  clothed  with  vines 
to  a  height  of  six  feet  a  strong  windstorm 
exerts  a  tremendous  leverage  on  them.  If 
the  sticks  have  not  been  inserted  deeply, 
or  if  they  have  become  dead  and  brit- 
tle, the  row  will  go  down  under  the  force 
of  the  wind  and  the  great  weight  of  the 
wet  vines.  In  order  to  guard  against  dis- 


42     CULTURE  OF  THE  SWEET  PEA 

aster,  strong  stakes  are  sometimes  placed 
every  ten  feet  and  wire  is  run  lengthwise 
through  the  sticks  and  fastened  to  the 
stakes.  It  is  desirable  to  have  the  sticks 
more  bushy  at  the  top  than  at  the  base,  so 
that  they  spread  out  more  than  at  the  base ; 
if  not  naturally  so,  leaning  the  sticks  alter- 
nately outward  will  produce  this  result. 
This  method  gives  greater  freedom  for  the 
vines  when  they  are  in  flower. 

After  the  sticks  are  inserted,  a  better  ef- 
fect is  produced  if  the  tops  are  clipped  to 
a  level  and  straggling  ends  are  cut  back. 
If  the  sticks  are  not  "feathered"  suffi- 
ciently at  the  base  for  the  plants  to  start 
up  on  them,  the  clippings  from  the  tops 
may  be  inserted  between  the  tall  sticks. 
Some  growers  make  a  practice — and  it  is 
a  good  one — of  providing  a  light  support 
when  the  plants  are  one  to  three  inches 
high,  and  later  placing  the  tall  sticks.  For 


HISTORY  AND  EVOLUTION        43 

the  light  support  they  often  use  old  rasp- 
berry canes,  in  fact,  anything  of  a  light, 
much-branched  character.  This  affords 
protection  from  high  winds  when  the 
plants  are  small. 

NETTING.  When  other  systems  of  sup- 
porting are  to  be  employed,  it  is  quite  im- 
perative to  provide  a  support  of  small, 
short  twigs  as  soon  as  the  seedlings  begin 
to  produce  tendrils.  This  method  pre- 
vents the  rain  from  beating  the  small 
plants  down,  and  enables  them  to  get  up 
to  the  other  support.  In  city  gardens, 
owing  to  the  difficulty  in  procuring  suit- 
able sticks,  wire  netting  makes  a  very  sat- 
isfactory support.  The  peas  do  not  cling 
to  it  so  well,  but  it  is  cleaner  and  neater 
in  appearance,  and  thus  offers  a  compen- 
sating advantage.  The  large  mesh  (four- 
inch)  is  preferable;  but  in  many  places 
this  is  not  procurable  and  the  ordinary 


44    CULTURE  OF  THE  SWEET  PEA 

chicken  netting,  or  fence,  is  used  instead. 
Strong  stakes  at  intervals  not  to  exceed  ten 
feet  are  used  to  support  the  netting.  One 
advantage  of  wire  netting  is  that  if  stakes 
six  feet  high  are  used,  a  forty-two  or  forty- 
eight-inch  strip  of  netting  may  be  placed 
in  position;  and,  if  the  season  or  soil  is 
favorable  and  the  peas  grow  above  this,  a 
narrow  strip  of  netting  may  be  added  or 
a  string  or  wire  stretched  from  stake  to 
stake  over  the  row.  A  well-galvanized 
netting  can  be  used  repeatedly  for  several 
years,  and  will  last  longer  if  taken  off  in 
the  fall  and  stored. 

STRING.  Another  method  is  to  con- 
struct a  support  of  wire  and  string,  or  of 
string  alone.  The  ingenious  grower  can 
construct  all  sorts  of  fanciful  designs  with 
wire  and  string  on  posts  set  not  over  ten 
feet  apart.  Sometimes  a  wooden  strip  is 
nailed  horizontally  at  the  top  and  bottom, 


HISTORY  AND  EVOLUTION        45 

but  often  a  wire  is  used  instead.  From 
bottom  to  top,  between  these  horizontal 
strips  or  wires,  a  homemade  network  can 
be  constructed.  When  the  peas  are  grown 
in  double  drills,  the  construction  described 
above  is  made  on  each  side  in  box-like 
form. 

When  sweet  peas  are  grown  in  single 
drills,  especially  on  a  considerable  scale, 
the  best  and  cheapest  support  is  one  made 
by  placing  stakes  at  intervals  of  less  than 
ten  feet  and  winding  strong  cord  around 
the  row  from  stake  to  stake.  The  strings 
are  placed  six  to  eight  inches  apart,  or 
closer  if  necessary.  If  the  stakes  are  too 
far  apart — ten  feet  or  more — the  string 
will  stretch  after  becoming  wet  or  even 
damp,  and  the  plants  will  fall  over.  If 
appearance  is  not  an  object,  anything  will 
serve  for  stakes,  e.g.,  tailings  from  the 
mills,  poles,  and  the  like.  If  neat  stakes 


46    CULTURE  OF  THE  SWEET  PEA 

are  used,  the  string  method  is  very  good 
for  the  garden  as  the  vines  cling  to  it  bet- 
ter than  to  wire  netting,  which  furthermore 
becomes  hot  in  the  summer.  At  the  end 
of  the  season,  if  the  stakes  are  worthless, 
the  whole  support  as  well  as  the  vines  may 
be  burned. 

The  foregoing  method  applies  to  sweet 
peas  grown  in  rows.  Sweet  peas  are  some- 
times grown  in  clumps  and  must  be  sup- 
ported. Here  again  sticks  are  often  fa- 
vored, especially  where  the  plants  occupy 
a  circle  six  feet  or  more  in  circumference. 
Wire  netting  cut  in  suitable  lengths  may 
be  made  into  cylinders  for  clumps  of  any 
size. 

Henry  Eckford  recommends  a  sweet  pea 
support  consisting  of  four  stakes,  each  in 
two  pieces  three  feet  long.  These  are 
placed  ninety  degrees  apart  around  a  cir- 
cle and  three-foot  netting  is  stretched 


HISTORY  AND  EVOLUTION        47 

around  them.  When  the  peas  reach  the 
top,  if  greater  height  is  needed,  the  upper 
half  of  each  stake  is  fitted  by  means  of  a 
mortise  into  the  top  of  the  one  already 
driven  and  another  strip  of  netting  is  put 
on. 

An  English  seedsman  advertises  sweet 
pea  ladders  for  use  in  training  the  vines  in 
garden  decoration.  The  ladders  are  made 
six  feet  long  and  six  inches  wide.  They 
are  used  perpendicularly,  the  tops  being 
fastened  to  a  horizontal  wire.  Two  rows 
are  supported  by  leaning  the  tops  together 
and  fastening  them  to  an  overhead  hori- 
zontal wire.  Plants  grown  in  circles  may 
be  brought  together  in  the  center  at  the 
top  where  the  ladders  are  fastened  to  a 
center  stake.  Sweet  pea  arches  about  six 
feet  high  are  sometimes  made. 

The  ladders  can  be  easily  made  with 
two  No.  10  galvanized  wire  rose  stakes  of 


48    CULTURE  OF  THE  SWEET  PEA 

the  proper  length,  and  some  smaller  wire 
for  the  rungs  or  cross  wires.  These,  of 
course,  should  never  be  over  six  feet  high 
or  they  would  seldom  be  covered.  The 
arches  can  also  be  made  complete,  if  de- 
sired, by  merely  making  the  ladder  long 
enough  and  bending  it  into  the  form  of 
an  arch. 

CULTIVATION 

TILLAGE.  Sweet  peas  need  frequent 
cultivation.  A  loose  dust  mulch  upon  the 
surface  must  be  constantly  maintained  in 
order  to  retain  the  moisture  for  the  plants. 
Amateurs  often  fail  because  they  do  not 
cultivate  their  sweet  peas,  but  depend 
upon  artificial  watering,  which  will  not 
bring  the  same  results  as  stirring  the  soil. 
The  surface  should  be  kept  loose  with  a 
rake,  and  if  this  condition  is  maintained 
there  is  usually  little  need  of  artificial 
watering. 


HISTORY  AND  EVOLUTION        49 

WATERING.  This  practice  often  results 
in  more  harm  than  good.  During  periods 
of  drought  it  may  be  advisable  to  apply 
water.  If  so,  apply  liberally  so  that  the 
soil  is  thoroughly  soaked.  It  is  also  im- 
portant to  remember  that  having  begun 
to  water,  it  is  necessary  to  keep  it  up  until 
the  rains  come.  Two  or  three  applications 
a  week  will  probably  be  required. 

MULCHING.  A  mulch  of  thoroughly 
rotted  manure  around  the  plants  will  as- 
sist in  lessening  the  effects  of  a  drought; 
or  if  water  is  also  applied,  the  mulch  will 
enable  the  plants  to  get  the  benefit  of  it 
by  preventing  rapid  evaporation. 

DISPODDING.  A  long  period  of  bloom 
cannot  be  had  unless  the  seed-pods  are 
consistently  picked  off.  Even  the  best  cul- 
tural methods  go  for  naught  unless  this 
operation  is  given  careful  attention.  The 
importance  of  watering  has  been  over  em- 


50    CULTURE  OF  THE  SWEET  PEA 

phasized,  whereas  the  true  explanation  of 
success  lies  in  the  removal  of  all  pods  as 
soon  as  the  flowers  wither.  If  delayed  un- 
til the  seed-pods  are  well  developed,  their 
removal  is  of  little  benefit  to  the  plant. 
If  one  desires  to  save  seed,  it  is  best  to 
mark  vigorous  plants  and  save  seed  from 
them.  As  the  plants  usually  flower  freely, 
few  plants  are  necessary  to  supply  all  the 
seeds  required  by  the  amateur.  All  plants 
not  required  for  seed  production  should  be 
kept  free  of  seed-pods  so  that  they  will 
continue  to  produce  flowers.  Cutting  all 
of  the  best  flower  spikes  does  not  produce 
the  desired  results,  unless  the  plants  are 
gone  over  frequently,  many  short-stemmed 
or  inferior  flowers  will  form  pods  and  in 
a  very  short  time  the  strength  of  the  plant 
will  be  utilized  in  developing  these  in  the 
effort  to  reproduce  itself.  To  obtain  good 
flowers  for  the  longest  period  of  time  the 


HISTORY  AND  EVOLUTION        51 

grower  must  destroy  promptly  and  thor- 
oughly the  withered  flowers. 

An  English  sweet  pea  expert  has  con- 
cisely summarized  sweet  pea  culture  as 
follows : 

"Sweet  Pea  Culture,  condensed  in  these 
words.  Trench  deeply;  manure  liberally; 
plant  thinly;  stake  quickly;  water  freely; 
dispod  promptly." 

MARKETING 

PICKING.  The  ideal  time  to  pick  sweet 
peas  is  two  or  three  hours  before  they  are 
needed  or  are  to  be  placed  on  the  market. 
This  length  of  time  is  the  period  the 
blooms  should  remain  in  water.  During 
this  period  many  varieties  will  improve  in 
size  and  color,  and  of  course  it  is  desirable 
to  have  flowers  at  their  best  when  they  are 
to  be  sold. 

If  the  flowers  are  to  be  shipped  to  mar- 


52    CULTURE  OF  THE  SWEET  PEA 

ket,  the  time  in  transit  must  be  added. 
These  factors  will  govern  the  time  of  pick- 
ing. It  is  best,  however,  to  pick  in  the 
morning  or  late  afternoon. 

The  stage  at  which  the  flower  spikes  are 
picked  will  depend  upon  the  foregoing 
factors,  and  also  upon  the  weather  and 
temperature  conditions.  The  spikes  ought 
to  be  picked  when  the  upper  flower  is 
about  one-half  open. 

In  picking,  a  knife  or  scissors  should  not 
be  used,  but  the  spikes  should  be  pulled. 
A  quick  side  pull,  while  holding  the  stem 
near  the  base,  will  usually  accomplish  the 
result  without  damage  to  the  plant.  As 
soon  as  picked,  the  flowers  should  be 
placed  in  water.  Vases  about  eight  inches 
in  diameter,  and  the  same  in  depth,  are 
about  right,  since  the  stems  can  be  plunged 
six  or  seven  inches.  Sometimes  eight-inch 
pots  are  taken  and  the  bottom  opening 


HISTORY  AND  EVOLUTION        53 

plugged  up  so  as  to  make  sweet-pea  vases. 
These  are  excellent  because  they  have  the 
best  form  to  keep  the  flowers  in  the  proper 
position. 

PACKING 

Sweet  peas  are  bunched  before  packing, 
twenty-five  flowers  usually  being  put  in 
each  bunch.  If  the  bunches  are  made  flat 
instead  of  round,  they  will  pack  much  bet- 
ter. Tie  the  stems  near  the  base  and 
never  near  the  flowers.  A  flat  box  for  one 
or  two  layers  of  bunches  is  the  best  pack- 
age. The  corrugated  and  folding  paper 
boxes  will  probably  be  found  to  give  the 
best  results.  It  is  essential  that  the 
bunches  be  packed  tight  enough  to  prevent 
bruising.  Some  make  a  practice  of  wrap- 
ping each  bunch  in  wax  paper.  The  boxes 
should  be  properly  lined  with  paper  before 
the  bunches  are  put  in. 


54    CULTURE  OF  THE  SWEET  PEA 

EXHIBITING  SWEET  PEAS 

The  foundation  for  success  in  raising 
sweet  peas  for  exhibition  is  laid  the  previ- 
ous autumn  in  the  thorough  preparation 
of  the  soil,  followed  by  a  careful  selection 
of  varieties,  thin  planting,  and  liberal  cul- 
ture. In  order  that  good  flowers  may  be 
obtained  for  exhibition,  it  is  best  to  remove 
all  flowers  about  a  week  before  the  date 
of  the  exhibition,  and  to  allow  only  the 
spikes  with  the  longest  stems  to  develop. 
The  size  of  the  flowers  may  be  increased  at 
this  time  by  the  use  of  ammonia  or  nitrate 
of  soda  applied  to  the  soil. 

All  varieties  subject  to  scorch  or  scald 
should  be  shaded  with  cheesecloth  or  tif- 
fany. If  such  varieties  are  planted  to- 
gether, the  shading  may  be  more  easily  ac- 
complished. The  varieties  which  have 
orange  in  their  coloration — that  is,  Henry 


HISTORY  AND  EVOLUTION        55 

Eckford,  St.  George,  and  Helen  Lewis — 
the  salmon  varieties,  and  possibly  some  of 
the  scarlets  and  blues,  should  be  shaded 
for  four  to  six  days  previous  to  the  time 
the  flowers  will  be  needed.  The  shade 
should  be  so  arranged  that  it  can  be  re- 
moved at  night. 

The  sweet  peas  having  been  well  grown, 
with  stems  twelve  to  fifteen  inches  long, 
the  next  consideration  is  the  cutting  of  the 
flowers;  for  it  is  one  thing  to  grow  good 
flowers,  and  quite  another,  but  equally  dif- 
ficult, to  exhibit  successfully. 

Sweet  pea  flowers,  especially  for  exhi- 
bition, should  be  cut  while  dry,  preferably 
in  the  morning  or  evening.  The  proper 
stage  of  development  will  depend  on  the 
number  of  hours  that  must  elapse  before 
the  judge  can  pass  upon  the  exhibit. 
Flowers  cut  the  day  before  exhibiting 
should  be  taken  with  the  lower  flowers 


56    CULTURE  OF  THE  SWEET  PEA 

open  and  the  top  ones  in  bud.  Those  with 
four  flowers  on  a  spike  may  be  taken  with 
the  two  lower  flowers  open,  the  third  flower 
opening,  and  the  topmost  one  in  bud. 
The  flowers  should  be  placed  immediately 
in  cool  water  and  removed  to  a  cool,  dark 
room  or  cellar  until  they  are  packed. 
Here  they  are  left  until  the  latest  moment 
consistent  with  their  timely  arrival  at  the 
exhibition  hall,  not  more  than  six  or  seven 
hours  if  possible. 

When  packing,  the  stems  should  be 
squeezed  in  order  to  remove  surplus  water 
and  then  wrapped  in  a  strip  of  oiled  paper. 
Great  care  should  be  exercised  not  to  get 
water  on  the  flowers.  Each  bunch  should 
be  wrapped  in  tissue  paper  and  the 
bunches  packed  not  too  tightly  as  to  crush 
the  flowers. 

Everything  is  necessary  to  insure  the 
prompt  arrival  of  the  flowers  at  the  exhi- 


HISTORY  AND  EVOLUTION        57 

bition  hall,  where  they  are  unpacked  and 
loosely  arranged  so  that  they  may  resume 
their  natural  form  after  the  journey. 

The  flowers  having  been  put  in  water, 
the  work  of  arranging  the  exhibition  vases 
should  begin.  George  W.  Kerr,  an  ex- 
perienced exhibitor,  gives  the  following 
directions  for  the  arrangement  of  flowers : 

"In  staging  the  flowers  never  crowd 
them.  Let  every  flower  'speak  for  itself.' 
Twenty  sprays  make  a  nice  vase,  and  the 
best  method  of  arranging  them  is  to  start 
by  putting  some  grass  (cut  two  inches 
long)  in  the  mouth  of  the  vase,  as  this 
helps  to  keep  the  stems  in  position.  Each 
stem  must  be  put  in  separately.  Let  every 
flower  be  seen  as  far  as  possible  and  all 
face  one  way,  with  the  exception  of  such 
varieties  as  have  the  back  of  the  standards 
tinted  in  coloring  other  than  the  ground 
color  of  the  flower,  when  the  position  of 


58    CULTURE  OF  THE  SWEET  PEA 

such  might  be  judiciously  varied.  One  or 
two  pieces  of  foliage — a  little  Gysophila 
— or  light  grass,  such  as  Agrostis  neublosa, 
might  with  advantage  be  used.  But  this 
should  not  be  overdone,  and  only  if  the 
rules  allow  of  it. 

"In  staging  a  collection  of  twelve  varie- 
ties, they  should  be  placed  in  three  rows, 
the  back  rows  being  tiered  eight  or  nine 
inches  above  the  other,  and  arrange  the 
colors  so  that  they  do  not  clash.  Even  if 
the  show  schedule  does  not  ask  for  it,  name 
each  variety  with  a  neat  card  placed  at  the 
base  of  each  vase." 

Two  very  important  points  for  the  ex- 
hibitor to  observe  are:  (i)  follow  the 
rules  as  to  the  number  of  stems  per  vase 
and  foliage  allowed;  (2)  see  to  it  that  the 
flowers  are  true  to  name.  Varieties  of  dis- 
tinct colors  should  be  used  and  those  that 
are  very  nearly  like  others  in  the  exhibit 


HISTORY  AND  EVOLUTION        59 

excluded.  Finally,  in  placing  the  vases, 
it  is  important  not  to  lose  sight  of  the  fact 
that  a  good  color  scheme  is  a  great  aid  to 
success. 


CHAPTER  II 

IF   SWEET    PEAS 

LAYMEN  who  visit  a  large  seed  farm  in 
California  marvel  at  the  acreage  of  sweet 
peas  in  that  state  and  wonder  how  the 
enormous  output  will  be  disposed  of.  But 
it  must  be  borne  in  mind  that  California 
grows  fully  75  per  cent  of  the  sweet  peas 
used  all  over  the  world.  About  50  per 
cent  of  the  sweet  peas  grown  in  California 
are  exported.  Of  these  much  is  sent  to 
Great  Britain,  the  remaining  50  per  cent 
to  Holland,  France,  Germany,  New  Zea- 
land, and  Australia.  The  gardening  pub- 
lic of  Great  Britain,  aided  by  the  seeds- 
men, quickly  realized  the  possibilities  of 
the  sweet  pea  as  an  exhibition  and  decora- 

1  By  C.  C.  Morse  and  Co.  of  California. 
60 


CULTURE  FOR  SEED  61 

ti ve  flower.  Other  countries  are  now  grad- 
ually taking  more  sweet  peas  and  the  fu- 
ture may  bring  a  larger  export  business. 
In  the  United  States  only  a  small  propor- 
tion of  sweet  peas  is  grown.  However, 
the  public  is  beginning  to  grow  more  of 
that  flower  every  year,  and  especially  the 
newer  Spencer  types.  On  an  everage 
the  acreage  of  sweet  peas  in  California 
is  about  2000  acres  with  about  50  per 
cent  Grandifloras,  and  50  per  cent 
Spencers.  The  value  of  this  crop  to  the 
growers  is  about  $250,000.  The  crop  ob- 
tained from  an  acre  of  sweet  peas  varies 
very  largely  according  to  season,  but  an 
average  yield  of  Grandifloras  would  be 
about  800  Ib.  per  acre;  that  of  a  good 
strain  of  Spencers  about  250  Ib.  per  acre. 
Owing  to  the  peculiar  formation  of  the 
floral  parts,  the  Spencers  are  not  so  prolific 
as  the  Grandifloras.  In  the  latter  the  keel 


62    CULTURE  OF  THE  SWEET  PEA 

of  the  flower  is  clamped,  enclosing  the 
stigma  and  the  anthers;  whereas  in  the 
Spencers,  the  keel  is  full  or  open  and  the 
stigma  protrudes  farther  out  than  the 
anthers,  thus  interfering  with  complete 
pollination.  It  would  be  hard  to  esti- 
mate the  value  of  the  sweet  pea  seed  to  the 
wholesalers  and  retailers  of  the  United 
States,  but  it  is  safe  to  put  it  down  to  about 
$600,000.  There  is  no  acreage  of  sweet 
peas  worth  mentioning  grown  in  the 
United  States  outside  of  California.  A 
few  acres  of  high  class  varieties  are  grown 
in  England  and  in  the  other  countries 
above  mentioned.  Except  in  cases  of 
stock  seed  of  new  varieties,  no  sweet  pea 
seed  is  imported  in  California. 

When  most  people  think  of  California 
as  a  seed  growing  state,  they  have  the  idea 
that  it  is  a  land  where  the  only  thing  the 
grower  has  to  do  is  to  plant  and  to  harvest, 


CULTURE  FOR  SEED  63 

and  that  California  does  the  rest.  The 
seedman  in  California,  however,  has  his 
trials  and  troubles  like  all  others  and  he 
has  all  the  scope  he  wants  for  his  practical 
ingenuity;  probably  there  is  more  need  of 
it  there  than  in  any  other  state  or  country. 
It  may  surprise  many  to  learn  that  there 
are  comparatively  few  valleys  or  parts  of 
valleys  suitable  for  sweet  peas  in  Califor- 
nia. This  in  itself  already  offers  the 
grower  a  chance  to  use  the  best  of  his  skill 
and  ingenuity.  In  California,  the  sweet 
pea  does  best  in  a  rich  heavy  loam  or  a  rich 
sediment  soil.  Too  heavy  and  too  sandy 
soils  are  unfit  for  that  plant. 

The  best  climate  is  one  which  never  gets 
too  hot  during  flowering  season,  and  the 
best  results  have  been  obtained  in  valleys 
where  the  fog  rolls  in  from  the  ocean  in  the 
evening,  keeping  the  air  moist  and  cool. 
A  hot  spell  during  blossoming  is  often 


64    CULTURE  OF  THE  SWEET  PEA 

fatal  to  the  crop,  especially  if  it  is  grown 
on  light  land;  and  if  the  rainfall  has  been 
slight  even  on  the  heavier  lands,  the  vines 
burn  up  completely.  When  the  soil  is  of 
a  loamy  character  and  the  climate  foggy, 
fifteen  inches  of  rain  are  sufficient  to  carry 
the  crop. 

The  land  is  best  when  dry  plowed,  just 
as  soon  as  the  previous  crop  is  off  in  the 
fall.  Thus  when  the  rain  works  through 
the  clods  the  particles  of  soil  crumble  and 
become  pulverized,  leaving  the  soil  in 
good  shape  for  early  planting.  In  Cali- 
fornia it  has  not  been  found  necessary  as 
yet  to  apply  any  fertilizer  to  sweet  peas. 
They  can  be  grown  year  after  year  on  the 
same  land,  often  producing  better  crops 
each  year,  provided,  of  course,  that  dis- 
eases are  kept  out.  To  get  the  best  results 
in  California,  sow  the  seeds  in  November 
or  December  if  possible.  As  soon  as  the 


CULTURE  FOR  SEED  65 

clods  can  be  broken  down  by  a  disk  plow 
or  harrow,  the  work  should  be  started. 
The  peas  are  drilled  in  rows  about  three 
feet  apart  by  a  two-horse  drill,  sowing  two 
drills  at  a  time  and  from  eight  to  fifteen 
pounds  per  acre.  The  acreage  which  can 
be  sown  per  day  depends  upon  many 
things  such  as  the  condition  of  the  land 
and  the  size  of  the  plot  to  be  planted,  but 
an  average  of  ten  acres  per  day  would  be 
about  right.  The  planter  is  set  to  place 
the  seeds  about  one  inch  deep,  this  being 
deep  enough  for  California  conditions. 

When  the  plants  are  high  enough  so  that 
the  rows  may  be  easily  seen,  the  field  is 
cultivated  by  a  two-horse  "riding"  culti- 
vator; and  if  the  weeds  have  started,  the 
plants  are  given  their  first  hoeing.  Dur- 
ing the  months  of  February,  March,  and 
April,  the  cultivators  are  kept  going  over 
the  field  until  the  meeting  of  the  vines  be- 


66    CULTURE  OF  THE  SWEET  PEA 
tween  the  rows  prevents  further  cultiva- 
tion.   It  is  generally  necessary  to  hoe  the 
crop  three  times. 

Sweet  peas  are  never  given  supports  or 
stakes  in  California.  The  vines  meet  in 
the  rows  and  by  supporting  one  another 
soon  grow  to  quite  a  height.  In  a  good 
season  they  may  grow  five  or  more  feet 
high.  In  California  each  plant  sends  out 
a  very  large  number  of  shoots  immediately 
above  ground  so  that  the  fields  are  very 
thick  and  in  flowering  season  are  just  one 
mass  of  blossom. 

The  most  important  problem  is  that  of 
"rogueing"  and  of  selection.  This  is  es- 
pecially the  case  with  Spencer  sweet  peas. 
The  stock  seed  should  be  right;  otherwise 
enormous  expense  and  labor  are  entailed 
in  rogueing  the  great  mass  of  plants  in 
flower,  and  great  damage  is  done.  Should 
some  rogues  be  allowed  to  seed,  the  stock 


CULTURE  FOR  SEED  67 

is  not  only  reduced  in  value,  but  the  land 
that  the  variety  is  grown  on  is  fouled  for 
all  time.  Sweet  peas  will  volunteer  for 
five  or  six  years,  often  longer.  It  may 
thus  readily  be  seen  that  it  pays  the  grower 
to  be  careful  of  his  stock  when  sweet  pea 
land  is  scarce.  Rogueing  sweet  peas  con- 
sists in  taking  out  all  wrong  colors  and 
wrong  types.  The  color  rogues  are  fairly 
easy  to  see,  but  it  takes  a  trained  eye  to 
pick  out  the  type  rogues;  and  this  work 
has  to  be  most  carefully  done.  Should  a 
Grandiflora  plant  be  allowed  to  remain  in 
a  crop  of  Spencers,  it  would  spoil  the  lat- 
ter in  a  short  time.  The  rogues  are  cut 
out  with  a  knife  below  the  level  of  the 
ground  so  that  the  plant  will  not  sprout 
again  and  give  further  trouble. 

The  careful  grower  has  his  stock  seed 
grown  and  selected  carefully  before  he 
plants  his  acreage.  He  knows  the  pedi- 


68    CULTURE  OF  THE  SWEET  PEA 

gree  of  his  stock  and  if  he  has  done  his 
work  thoroughly  he  can  depend  on  a  crop 
true  to  type. 

The  season  of  harvest  varies.  Cutting, 
which  is  done  with  the  mower,  usually 
commences  in  July.  Judgment  must  be 
exercised  as  to  the  proper  time  for  har- 
vest. The  vines  are  ordinarily  cut  when 
it  is  considered  that  most  of  the  pods  are 
ripe.  Immediately  after  cutting,  the  vines 
are  piled  on  large  pieces  of  canvas  which 
are  placed  on  the  ground  where  the  crop 
has  been  growing.  These  sheets  are  gen- 
erally forty  feet  square.  When  the  vines 
are  thoroughly  dry  the  thrasher  and  sepa- 
rator are  hauled  to  the  patch  and  a  port- 
able gasoline  engine  supplies  the  driving 
power.  The  fields  of  sweet  peas  are  so 
planned  that  the  thresher  will  not  by  any 
chance  let  any  seed  drop  elsewhere  than 
on  the  area  occupied  by  the  variety.  After 


CULTURE  FOR  SEED  69 

each  variety  is  finished  the  separator  is 
thoroughly  cleaned  out  and  run  empty  for 
a  while  so  that  no  seed  will  be  left  in  to 
mix  with  the  next  variety  to  be  threshed. 
Stock  seed  is  generally  threshed  by  flail 
in  order  to  avoid  all  possible  chance  of 
mixture.  After  this  the  seed  is  taken  to 
the  cleaning  house  and  put  through  a  se- 
ries of  fans  and  screens  to  take  out  all 
chaff  and  small  and  broken  seeds. 

The  raising  of  new  varieties  is  very  in- 
teresting. All  careful  breeders  work  on 
the  Mendelian  principle,  and  since  the 
realization  of  the  importance  of  these  laws, 
there  has  been  less  unfixed  stock  put  on 
the  market.  The  following  is  a  brief 
statement  of  the  procedure  for  raising  new 
varieties.  The  flower  to  be  pollinated 
must  be  in  a  very  young  stage,  generally 
a  bud  before  the  color  even  begins  to 
show.  As  the  sweet  pea  blossom  sheds  its 


70    CULTURE  OF  THE  SWEET  PEA 

pollen  in  the  bud  stage,  the  selection  has 
to  be  made  carefully.  The  buds  being  se- 
lected, the  keel  is  split  open  with  a  sharp 
knife  and  all  the  stamens  are  carefully  re- 
moved. The  stigma  is  carefully  examined 
to  see  that  no  pollen  has  been  deposited 
accidentally.  Then  pollen  is  carefully 
gathered  from  the  other  parent  and  depos- 
ited with  a  fine  camel's  hair  brush  on  the 
stigma  of  the  flower  from  which  the  sta- 
mens have  been  removed.  The  artificially 
pollinated  blossom  is  now  wrapped  in  a 
paper  bag  which  is  securely  fastened  to  ex- 
clude all  possibilities  of  further  pollina- 
tion. It  is  necessary  to  make  a  large  num- 
ber of  such  crosses  to  obtain  results,  as  it 
often  happens  that  a  large  per  cent  of  the 
flowers  thus  crossed  fail  to  set  seed.  The 
seeds  from  the  successful  crosses  are  care- 
fully gathered  and  planted  separately  the 
second  year  (figs.  2  and  3) .  No  particu- 


Fig.  2. — Trial  grounds  of  C.  C.  Morse  and  Co.,  San  Juan, 
Cal. 


Fig.  3.— Field  of  Morse's  White  Spencer  on  C.  C.  Morse 
and  Co.'s  Sweet  Pea  ranch  at  San  Juan,  Cal. 


CULTURE  FOR  SEED  71 

lar  notice  need  be  paid  to  the  plants  of  the 
first  year's  cross;  and  all  the  seeds  may  be 
saved  together.  The  second  year,  how- 
ever, it  will  be  found  that  there  is  a  large 
variety  of  blossoms.  Close  inspection  is 
then  given  to  each  plant  to  determine 
whether  it  has  the  merits  desired.  Some 
plants  will  no  doubt  be  found  to  contain 
special  merits ;  their  seeds  should  be  saved 
separately  and  grown  another  year  or 
two  to  determine  if  they  will  come  true 
to  type. 

Every  careful  seed  grower  must  operate 
for  his  seed  peas  a  trial  ground  in  which 
are  grown  all  varieties  for  comparison  and 
test.  A  sample  of  each  crop  is  taken  be- 
fore it  is  shipped  to  the  customer  and  a 
sample  of  all  selected  stock  is  taken.  The 
various  samples  of  each  variety  are  ar- 
ranged together  and  any  novelty  of  simi- 
lar color  is  also  arranged  with  the  variety 


72    CULTURE  OF  THE  SWEET  PEA 

which  it  is  said  to  supersede.  The  sam- 
ples are  planted  alongside  each  other. 
Trial  ground  rows  are  generally  about  ten 
steps  long,  and  a  six-foot  space  is  left  be- 
•tween  the  rows.  Each  sample  is  given  a 
number  which  is  recorded.  If  rogues  ap- 
pear, their  percentage  is  noted.  Improve- 
ment in  select  stock  seed  is  looked  for  and 
a  value  put  on  each  novelty.  The  trial 
ground  is  an  important  part  of  the  equip- 
ment of  the  seed  farm,  and  too  much  study 
and  time  cannot  be  given  to  it.  Points  to 
be  noted  in  judging  a  stock  seed  are  the 
size  of  flower,  length  of  stem,  number  of 
flowers  on  each  stem,  color,  brightness  and 
lasting  quality,  texture  of  flower,  vigor  of 
growth,  length  of  blooming  period,  and 
the  amount  of  seed  produced. 

The  sweet  pea  is  not  an  easy  crop  to  irri- 
gate and  it  can  be  done  only  with  care 


CULTURE  FOR  SEED  73 

and  judgment.  Generally  one  irrigation 
should  be  given  and  that  before  the  pods 
are  set  on  the  vines. 


CHAPTER  III 

CULTURE    OF   SWEET    PEAS    UNDER   GLASS  * 

THE  production  of  sweet  peas  under 
glass  is  being  extended  every  year  due  to 
increase  in  prominence  as  a  cut  flower,  and 
hence  their  economic  value  in  winter. 
Greenhouse  sweet  peas  as  a  cut  flower  rank 
third  on  the  market,  coming  after  the  roses 
and  carnations.  They  are  thus  grown  in 
nearly  every  state  in  the  Union,  usually, 
however,  in  the  vicinity  of  large  cities. 
Philadelphia,  New  York,  Buffalo,  Boston, 
Chicago,  Detroit,  Milwaukee,  Omaha,  St. 
Louis,  Kansas  City,  Denver,  and  a  num- 
ber of  other  large  cities  offer  good  mar- 
ket opportunities  for  winter  flowering 

1  Abstract  of  Commercial  Sweet  Pea  Culture  by  Ant. 
C.  Zvolanek. 


74 


CULTURE  UNDER  GLASS  75 

sweet  peas.  In  the  warmer  states  sweet 
peas  are  grown  out  of  doors  during  the 
winter,  requiring  but  very  little  shelter. 

For  sweet  peas  under  glass  it  is  neces- 
sary to  have  a  suitable  house  (see  Frontis.) . 
The  sides  of  the  house  should  be  at  least 
eight  feet  high,  the  upper  being  of  glass. 
If  the  houses  are  but  seven  feet  high,  the 
side  rows  strike  the  glass  when  the  vines 
are  about  half  grown,  thereby  giving  half 
a  crop.  The  ridge  of  the  house  should  be 
from  twelve  to  fifteen  feet  high.  The 
higher  the  vines  grow,  the  more  and  bet- 
ter flowers.  For  December  and  January 
cuttings,  large  houses  are  necessary  so  that 
the  sun  may  penetrate  every  corner. 
Sweet  peas  sown  in  October  as,  for  exam- 
ple, after  chrysanthemums,  will  not  bloom 
before  February. 

The  ideal  soil  is  sandy  loam.  Red  shell 
soil  is  good  if  taken  about  six  inches  below 


76    CULTURE  OF  THE  SWEET  PEA 

the  surface;  very  coarse  gravelly  soil  if 
well  fertilized  answers  the  purpose.  Soil 
taken  from  swampy  places,  provided  it  is 
not  heavy  clay,  is  good,  but  cannot  be  used 
the  same  year.  It  should  be  spread  out 
about  sixteen  inches  thick  on  high  ground 
and  left  there  to  winter  over.  The  rain 
will  wash  out  any  alkali  which  it  may  con- 
tain. In  the  following  spring,  about  June, 
compost  may  be  made  of  this  soil.  Some 
air  slaked  lime  and  coarse  bone  is  added, 
together  with  the  necessary  manure. 

Solid  beds  of  good  soil  two,  or  two  and  a 
half,  feet  in  depth  are  the  best.  If  sweet 
peas  follow  a  tomato  crop,  which  is  on  the 
wane  by  the  middle  of  August,  the  beds 
should  be  deeply  trenched,  bringing  the 
bottom  soil  to  the  surface.  In  the  bottom 
of  the  trench  three  inches  of  decomposed 
cow  manure  are  worked  in;  one  foot  from 
the  surface  three  inches  more  of  the  same 


CULTURE  UNDER  GLASS          77 

material  are  added.  The  house  is  allowed 
to  remain  in  this  condition  until  nearly 
time  for  sowing  the  seed.  The  soil  then 
is  usually  dry  and  needs  to  be  moistened 
enough  to  cling  together  when  it  is  worked 
next  time  with  the  spade.  This  time  it  is 
necessary  to  go  down  one  foot  and  mix 
the  top  layer  of  manure  with  the  surface 
soil ;  then  make  it  as  level  as  possible  and 
thoroughly  water  it  with  a  strong  dose  of 
liquid  horse  manure.  In  about  three  days, 
depending  on  the  weather,  the  house  will 
be  ready  for  the  planting. 

Sweet  peas  may  also  be  grown  on  a  bench 
with  a  few  inches  of  soil,  but  the  result  will 
be  a  weak  growth  and  a  crop  of  short 
stemmed  flowers.  These  soon  play  out,  as 
there  is  not  enough  soil  or  food  for  the 
vines  to  live  on. 

There  are  a  great  many  varieties  of  the 
winter  flowering  type  of  sweet  peas,  the 


78    CULTURE  OF  THE  SWEET  PEA 

old  grandiflora  being  the  best  known.  Ac- 
cording to  Zvolanek  the  new  Winter 
Orchid-flowering  sweet  peas  are  preferred 
to  the  old  type.  The  principal  thing  is  to 
select  the  best  selling  colors.  In  this  re- 
spect the  Pink  and  White  Orchids  seem 
to  have  no  equal  for  mid-winter  flowering. 
Of  the  white  varieties  there  are  the  White 
Orchid,  Bridal  Veil,  Venus,  and  Mrs.  M. 
Spanolin.  Of  those  of  lavender  shades 
the  best  are  Lavender  Orchid,  Lavender 
Pink,  and  Lavender  Nora,  which  is  a  clear 
lavender  of  the  Winter  Unwin  type.  The 
last  named  has  large  sized  flowers,  the 
average  of  which  are  as  large  as  any  of  the 
Orchid-flowering  type.  In  light  pink, 
there  are  Mrs.  A.  A.  Skach,  Mrs.  J.  Manda, 
and  Dolansky  Orchid.  In  dark  rose  there 
are  the  Orchid  Beauty  and  President  Wil- 
son. The  best  in  orange  pink  is  the 
Orange  Orchid,  and  to  this  the  Orange 


CULTURE  UNDER  GLASS  79 

Nora  and  Orange  Bird  are  close  seconds. 
Both  of  these  are  of  the  Winter  Unwin 
type.  The  colors  above  mentioned  are 
suitable  to  grow  in  large  quantities.  In 
the  dark  blue,  the  new  orchid-flowering 
Mrs.  M.  Anderson  is  commendable,  and 
second  only  to  the  Blue  Jay  or  the  Winter 
Unwin.  In  red,  the  Red  Orchid  is  the 
best.  All  light  pink  varieties  produce 
much  brighter  colors  if  grown  so  as  to 
bloom  after  the  middle  of  January,  when 
the  weather  is  sunnier  than  in  December. 
To  obtain  a  good  crop  of  flowers  for  the 
Christmas  trade,  seed  should  be  sown  any- 
where north  of  Washington,  D.  C.,  be- 
tween the  tenth  and  twentieth  of  August; 
this  time,  too,  will  depend  somewhat  on 
the  weather.  Warm  and  bright  days  in 
the  fall  at  the  time  of  sowing  will  help 
the  main  crop  in  maturing  early  in  Novem- 
ber when  the  price  of  sweet  peas  is  very 


8o    CULTURE  OF  THE  SWEET  PEA 

low.  On  the  other  hand,  if  the  weather  is 
cool  and  doudy  at  the  time  the  seed  is 
sown,  the  flowers  will  probably  be  too  late 
for  Christmas  trade.  It  is  much  better  to 
have  the  crop  in  January,  as  during  that 
month  and  the  following  months  the  prices 
are  usually  as  high  as  during  the  Christmas 
week. 

When  the  beds  have  been  well  prepared 
the  soil  is  pressed  down  and  raked  smooth. 
Rows  are  then  opened  at  least  five  feet 
apart  and  the  seed  sown  about  three  inches 
apart  in  the  row,  and  covered  to  about  one 
and  a  half  inches  deep.  Seeds  should  not 
be  sown  in  a  soil  which  is  too  wet  and 
sticky.  It  is  better  to  wait  a  few  days 
until  conditions  are  right.  White  sweet 
pea  seeds,  if  planted  in  dry  soil  and 
watered  soon  after  being  sown,  will  sel- 
dom germinate.  After  the  seed  is  sown, 
rake  the  surface  of  the  bed  very  fine  to  the 


CULTURE  UNDER  GLASS          81 

depth  of  about  one  inch.  This  raking  will 
make  a  fine  soil  mulch  on  the  top,  which 
conserves  the  moisture,  besides  keeping 
the  soil  cool,  a  condition  necessary  for  suc- 
cessful germination.  Under  these  condi- 
tions no  watering  will  be  necessary  for  at 
least  ten  days  or  as  long  as  moisture  may 
be  found  about  four  inches  below  the  sur- 
face. Sometimes  three  weeks  elapse  be- 
fore it  becomes  necessary  to  water  the  beds. 
This  method  encourages  the  seeds  to  send 
their  roots  deep  into  the  soil  in  the  direc- 
tion of  more  water.  Plants  with  deep 
roots  can  withstand  the  hottest  days  with- 
out damping  off,  a  condition  which  often 
follows  when  the  moisture  is  kept  on  the 
surface.  If  the  soil  becomes  too  dry  after 
a  while,  water  well  down  to  the  base,  keep- 
ing the  surface  well  worked.  After  sow- 
ing, the  temperature  should  be  kept  as  low 
as  possible;  and  if  the  seed  is  sown  in 


82    CULTURE  OF  THE  SWEET  PEA 

August  when  the  weather  is  extremely 
warm  the  glass  should  be  kept  white- 
washed as  long  as  the  hot  weather  con- 
tinues. After  the  seedlings  appear  above 
ground  they  may  be  sprayed  several  times 
each  day  during  hot  spells. 

To  prevent  slow  germination  the  seed 
may  be  soaked  in  water  for  about  fifteen 
hours  just  before  sowing.  This  will  cause 
the  seed  to  soften  and  swell  so  that  when 
sown  they  will  germinate  quickly.  Those 
which  still  remain  hard  after  the  soaking 
should  be  rubbed  against  a  fine  flat  file, 
taking  one  seed  in  each  hand  and  striking 
once  or  twice  over  the  file  just  enough  to 
cut  the  hard  skin.  The  seeds  treated  in 
this  way  should  be  dropped  back  into  the 
water,  and  within  another  fifteen  hours 
they  will  be  soft,  swollen,  and  ready  to 
sow. 


CULTURE  UNDER  GLASS          83 

After  the  sowing,  the  greenhouse  should 
be  kept  as  cool  as  possible,  admitting  air 
day  and  night  as  long  as  the  weather  will 
permit.  The  cooler  the  temperature  of 
the  house  when  the  plants  are  started  the 
stronger  and  healthier  they  become.  Late 
in  the  fall  some  heat  is  necessary.  The 
temperature  at  night,  however,  should  not 
be  higher  than  40  to  44  degrees  Fahren- 
heit; otherwise  the  young  plants  will  be- 
gin to  bloom  early  before  the  roots  have 
had  a  good  start.  The  winter  sweet  peas, 
if  sown  in  August  or  later,  and  properly 
cultivated,  should  be  at  least  thirty  inches 
high  before  the  blooms  appear.  Some- 
times during  warm  and  bright  days  in  the 
fall  the  plants  show  a  tendency  to  bud 
very  early.  In  this  case,  the  buds  should 
be  picked  off  as  soon  as  they  appear. 
When  the  plants  are  between  two  and  a 


84    CULTURE  OF  THE  SWEET  PEA 

half  to  four  feet  high,  they  should  all  be- 
gin to  bud.  At  this  time  the  temperature 
should  be  raised  every  night  by  one  or  two 
degrees.  If  the  temperature  averages  44 
degrees  F.,  make  it  45  degrees  the  next 
day,  and  so  on  until  52  is  reached.  This 
is  the  highest  and  safest  temperature  for 
the  older  winter  grandifloras  at  night. 
When  in  bloom,  the  temperature  may  be 
raised  to  60  degrees  F.  during  cloudy  days 
and  68  during  bright  days.  All  the  new 
Winter  Orchid-flowering  sweet  peas  in  the 
first  stage  need  the  same  treatment  as  that 
just  described  above.  But  as  these  begin 
to  bud  and  flower  the  temperature  should 
be  raised  to  55  degrees  F.  at  night,  60  to 
65  for  cloudy  days,  and  70  to  72  during 
bright  days.  This  higher  temperature  is 
necessary  for  the  new  strains,  as  the  flowers 
are  larger  and  the  number  to  a  single  stem 
correspondingly  more  numerous ;  the  addi- 


CULTURE  UNDER  GLASS          85 

tional  warmth  prevents  the  falling  of  the 
buds  and  encourages  brighter  colors. 

After  the  plants  have  reached  the  height 
of  about  six  inches  they  should  be  given 
something  to  climb  on.  The  best  and 
cheapest  way  is  to  run  one  wire  on  the  bot- 
tom and  another  from  eight  to  ten  feet 
above  each  row,  connecting  these  two 
wires  with  strings  as  is  done  in  the  grow- 
ing of  smilax.  Strings  should  also  be  run 
lengthwise  of  the  row,  about  every  ten 
inches,  as  the  plants  advance  in  growth. 
At  the  same  time  it  is  well,  occasionally, 
to  help  the  vines  to  climb  on  the  strings. 
The  upper  wire  must  be  the  strongest,  for 
when  the  sweet  peas  are  in  full  bloom  they 
are  usually  ten  feet  high,  and  the  vines  of 
one  row  one  hundred  feet  long  will  weigh 
over  a  ton.  If  at  any  time  the  upper  wire 
should  break,  all  the  flowers  become 
bruised,  crooked,  and  of  very  little  value. 


86    CULTURE  OF  THE  SWEET  PEA 

In  order  to  divide  the  weight,  wooden  or 
iron  supports  should  be  placed  under  the 
upper  wire  every  eight  feet. 

After  the  sweet  peas  have  been  in  bloom 
for  some  time  and  begin  to  produce  short 
peduncles  it  is  time  to  feed  them  a  little. 
The  best  food  is  liquid  or  pulverized  cow 
or  sheep  manure.  It  is  doubtful  if  nitrate 
of  soda  is  beneficial  then.  During  blos- 
soming the  house  should  not  be  fumigated 
with  hydrocyanic  gas  for  although  this 
will  destroy  many  insects  it  will  also  de- 
stroy most  of  the  buds  which  are  forming. 

It  is  preferable  to  pick  the  flowers  in  the 
afternoon,  as  at  that  time  the  greatest 
number  of  flowers  are  open.  Where  thou- 
sands of  flowers  are  picked  daily,  the  most 
experienced  help  should  go  over  the  rows 
first,  picking  only  the  best  blossoms  with 
the  longest  peduncles,  ten  selected  flowers 
to  a  bunch.  The  second  and  less  reliable 


CULTURE  UNDER  GLASS          87 

help  are  put  to  pick  the  second  grade  of 
blooms,  putting  twenty-five  sprays  to  a 
bunch;  and  finally  the  third  hands  should 
gather  all  the  crooked  and  short  stemmed 
blossoms.  If  the  flowers  are  to  be  shipped 
a  long  distance  to  be  sold  the  next  day, 
pick  all  flowers  having  three  or  more 
blooms  or  buds  to  a  stem.  As  soon  as  a 
certain  number  have  been  picked  they 
should  be  placed  in  water,  but  not  in  deep 
vases  or  large  pails  as  the  blossoms  may 
become  wet  and  lose  their  fragrance. 
After  the  flowers  have  stood  in  water  for 
about  three  hours  they  are  ready  to  be 
shipped. 

One  of  the  most  successful  crops  to  grow 
after  sweet  peas  is  tomatoes.  In  small 
and  moderately  warm  houses,  or  propagat- 
ing beds,  the  tomato  seed  is  sown  in  No- 
vember and  then  transplanted  in  small 
pots  and  repotted  several  times  afterwards 


88    CULTURE  OF  THE  SWEET  PEA 

until  the  plants  are  finally  placed  in  five-  or 
six-inch  pots.  After  Easter  the  sweet  peas 
which  are  then  beginning  to  play  out,  are 
replaced  by  these  tomato  plants.  They 
are  planted  16  to  20  inches  apart  and 
trained  to  a  single  stem.  By  June  or  July, 
the  tomato  crop  ought  to  be  on  the  wane 
and  the  house  is  at  once  prepared  again 
for  sweet  peas.  Violets  are  also  success- 
fully grown  in  rotation  with  sweet  peas. 
These  should  be  planted  the  latter  part  of 
September.  The  beds  should  be  five  to 
six  feet  wide,  with  a  space  of  twelve  inches 
on  the  north  side  for  one  row  of  sweet  peas, 
all  the  rest  being  planted  in  violets.  Both 
of  these  flowers  may  be  planted  at  the 
same  time,  since  the  violets,  too,  need  a 
low  temperature  not  over  40  degrees  F. 
The  sweet  peas  will  grow  slowly  at  first, 
probably  not  being  over  three  feet  in 
height  by  the  last  of  February.  By  this 


Fig.  4. — Sweet  Peas  and  Carnations  grown  in  the 

same  house. 
Courtesy  of  Lord  and  Burnham. 


CULTURE  UNDER  GLASS  89 

time  the  violets  will  have  almost  finished 
blooming,  or  at  any  rate  their  market  price 
will  be  low.  This  is  the  time  to  discard 
the  violets  and  to  raise  the  temperature  to 
suit  the  sweet  peas;  and  which  will  pres- 
ently produce  a  splendid  crop.  Chrys- 
anthemums or  carnations  (fig.  4)  may  also 
be  grown  with  sweet  peas.  In  a  house 
with  early  varieties  such  as  "Golden 
Glow"  and  "Pacific,"  the  chrysanthemums 
will  be  all  done  by  October  20th.  If 
sweet  peas  are  sown  in  four-inch  pots 
about  September  10th,  they  will  be  large 
enough  to  be  put  in  place  by  the  time 
the  chrysanthemums  are  gone.  The  soil 
should  be  prepared  and  the  sweet  peas 
planted  in  place  at  once,  so  that  they  may 
begin  to  bloom  by  the  latter  part  of  Janu- 
ary. Other  things  may  be  grown  between 
the  sweet  pea  rows,  namely,  all  kinds  of 
bulbs  and  flats  with  small  ferns. 


CHAPTER  IV 

DISEASES   OF   GREENHOUSE   SWEET    PEAS 

RECENT  investigations  have  shown 
that  failures  with  greenhouse  sweet  peas 
may  be  readily  accounted  for.  Sickness 
and  death,  not  considering  accidental 
death,  both  in  plants  as  in  animals,  are  due 
either  to  insects  or  to  certain  definite  forms 
of  parasitic  plant  life,  also  known  as  germs 
or  microbes.  Sweet  peas  need  plenty  of 
air  and  sunshine  and  a  cool  climate. 
These  conditions  are  far  from  being  satis- 
fied in  the  greenhouse.  Plants,  like  ani- 
mals, when  placed  in  unnatural  surround- 
ings, become  a  ready  prey  to  disease. 
Sweet  peas  under  greenhouse  conditions 
are  forced  to  grow  in  an  unnatural  way. 

The  parasitic  fungi  which  attack  sweet 
90 


DISEASES  IN  GREENHOUSE        91 

peas  are  minute  microscopical  forms  of 
plant  life,  devoid  of  the  green  matter 
known  as  chlorophyll.  Structurally,  a 
fungus  consists  of  one  cell  or  of  several 
cells,  connected  end  to  end,  forming 
threads  known  as  mycelium.  The  fungus 
gains  access  to  the  interior  tissue  of  the 
plant,  and  deprives  the  latter  of  the  food 
it  needs  for  its  welfare.  This  action  re- 
sults in  slow  death  or  in  a  sudden  collapse 
of  the  affected  host.  In  the  case  of  pow- 
dery mildew,  mentioned  later,  the  fungus 
lives  on  the  surface  of  the  leaves,  and  sends 
delicate  suckers  into  the  epidermis  to  ob- 
tain its  food  from  the  tissue  of  the  host. 

Parasitic  bacteria  are  smaller  forms  of 
life  than  are  the  fungi,  but  their  mode  of 
attack  is  not  very  different.  With  the  ex- 
ception of  the  large  mushrooms,  which  are 
also  fungi,  most  others  are  invisible  to  the 
naked  eye  and  must  be  studied  under  a 


92     DISEASES  OF  THE  SWEET  PEA 

compound  microscope.  When  grown  in 
pure  culture,  however,  they  are  plainly 
visible  as  colonies  of  aggregate  individ- 
uals. 

Insects  are  divided  into  two  classes :  one 
class  derives  its  food  by  sucking  the  plant 
juices  and  is  known  as  "suckers" ;  the  other 
class  chews  and  eats  solid  parts  of  roots, 
stems,  foliage,  or  blossoms,  and  is  known 
as  "biting."  All  insects  undergo  certain 
changes  (metamorphosis),  beginning  as 
larvae  and  ending  as  adult  beetles,  bugs, 
or  butterflies.  Not  all  animals  which  are 
parasitic  on  plants  are  insects,  as,  for  ex- 
ample, the  eel  worm.  The  latter  belongs 
to  the  Arthropoda  of  the  Animal  Kingdom, 
its  body  being  composed  of  many  segments 
with  no  legs. 

Red  spiders  and  mites,  likewise  plant 
parasites,  are  not  insects.  These  belong 
to  the  Arachnida  or  true  spiders.  Books 


DISEASES  IN  GREENHOUSE        93 

of  the  same  nature  as  the  present  work 
generally  discuss  fungi,  bacteria,  and  in- 
sects under  different  headings.  This 
precedent  will  not  be  closely  followed 
here,  but  all  three  will  be  taken  up  from 
the  point  of  view  of  their  economic  im- 
portance rather  than  in  the  light  of  their 
systematic  relationship. 

As  a  rule  plant  diseases  do  not  spread  so 
rapidly  in  the  greenhouse  as  in  the  field. 
The  restrictions  of  wind  currents  and  the 
lack  of  easy  access  of  insects  are,  no  doubt, 
factors  in  keeping  in  check  many  diseases. 
There  are,  however,  some  indoor  condi- 
tions such  as  moisture  and  temperature, 
which  if  not  properly  attended  to,  will  re- 
sult in  great  financial  loss  by  favoring  the 
spread  of  disease. 

Upon  proper  watering  depends  much  of 
the  success  of  crops  grown  under  glass. 
The  amount  of  water  and  the  way  it  is  ap- 


94     DISEASES  OF  THE  SWEET  PEA 

plied  as  well  as  the  amount  of  moisture  in 
the  air  of  the  greenhouse  may  determine 
the  presence  or  absence  of  disease.  A  rela- 
tively high  percentage  of  moisture  in  the 
soil  or  in  the  air  favors  damping  off.  The 
humidity  of  the  atmosphere  in  a  green- 
house is  usually  much  higher  than  that  out 
of  doors.  From  this  it  follows  that  good 
ventilation  should  be  provided.  Over- 
watering  of  sweet  peas  gives  rise  to  un- 
healthy conditions,  especially  in  cloudy 
weather,  when  evaporation  and  transpira- 
tion are  arrested.  Thus  the  soil  becomes 
flooded  with  water  which  interferes  with 
the  respiration  of  the  roots  and  the  plants 
become  more  susceptible  to  diseases  which 
may  be  present  in  the  soil  in  the  green- 
house. An  excess  of  moisture  in  the  air 
also  favors  the  development  and  spread 
of  the  powdery  mildew.  During  bright 
sunny  weather  there  is  little  danger  from 


DISEASES  IN  GREENHOUSE        95 

overwatering,  since  transpiration  and 
evaporation  are  then  very  active.  What 
is  true  of  "damping  off"  and  the  mildews 
is  also  true  for  root  knot.  The  minute  eel 
worms  cannot  thrive  unless  there  is  suffi- 
cient moisture  in  the  soil.  Neither  can 
they  thrive  in  soils  that  are  flooded,  since 
they  must  have  air  to  live.  This  is  taken 
advantage  of  in  open  fields  where  root 
knot  is  controlled  by  flooding  the  land. 
Overwatering,  or  any  form  of  injudicious 
watering,  is  no  doubt  an  important  factor 
in  predisposing  the  sweet  pea  plants  to  the 
attacks  of  Thielavia,  Rhizoctonia,  Chae- 
tomium,  and  Fusarium  root  rots.  It  is 
therefore  well  to  provide  some  means  of 
drainage,  especially  where  the  beds  are 
solid  and  in  the  ground.  It  is  a  good 
practice  to  lay  at  the  bottom  of  the  beds 
from  one-half  to  one  foot  of  ashes  or  a 
layer  of  broken  bricks  or  crushed  stones. 


96     DISEASES  OF  THE  SWEET  PEA 

This  will  help  to  drain  off  the  excess  of 
water  likely  to  be  applied  by  unskilled  or 
inexperienced  help. 

Water  is  not  the  only  important  factor 
in  controlling  or  increasing  fungous  pests 
under  glass.  Temperature  also  plays  an 
important  role.  Damping  off  of  green- 
house sweet  peas  is  best  controlled  by 
keeping  the  greenhouse  at  a  temperature 
of  50  to  60  degrees  F.  A  temperature  of 
80  to  90  degrees  F.  with  a  high  moisture 
content  of  the  air  will  cause  all  young 
seedlings  to  damp  off,  if  the  fungus  is 
present  in  the  soil.  It  is  doubtful  if  tem- 
perature greatly  influences  the  control  of 
collar  rot,  although  a  temperature  of  90 
degrees  will  be  more  favorable  to  the  fun- 
gus than  a  temperature  of  50  degrees  F. 
Nevertheless,  a  low  temperature  will  not 
considerably  check  this  disease  when  it 
once  gets  a  start.  In  greenhouses  where 


DISEASES  IN  GREENHOUSE       97 

collar  rot  has  become  established,  steriliza- 
tion of  the  soil  is  the  only  remedy.  Sweet 
peas  grown  in  the  greenhouse  are  subject 
to  moisture  conditions  quite  different  from 
those  grown  outdoors.  Natural  light  is 
less  in  winter,  and  in  order  to  induce 
growth  under  adverse  conditions  heat  is 
used  as  a  stimulant.  This  produces  plants 
readily  susceptible  to  disease.  As  these 
difficulties  cannot  be  avoided,  it  is  essen- 
tial to  start  with  sterilized  soil  in  the 
benches. 

Most  sweet  pea  growers  do  not  change 
their  greenhouse  soil  every  year.  As  time 
goes  by,  and  the  crop  is  grown  successively 
in  the  same  place,  the  soil  soon  becomes 
sour.  This  condition  naturally  tends  to 
encourage  the  development  of  a  parasitic 
flora  in  the  soil  which  is  detrimental,  to 
sweet  pea  culture. 

The  following  is  a  quick  method  to  de- 


98    DISEASES  OF  THE  SWEET  PEA 

termine  soil  acidity,  based  on  the  use  of 
litmus  paper,  devised  by  Mr.  J.  E.  Har- 
ris,1 who  found  that  some  kinds  of  litmus 
paper  are  not  suitable.  Experiments  have 
shown  that  Kahlbaum's  litmus  paper  is  the 
best  for  the  purpose.  It  is  so  sensitive  that 
it  is  necessary  to  leave  it  in  contact  with 
the  soil  particles  only  for  a  moment  or  two. 
Soil  only  very  slightly  acid  will  change  the 
litmus  paper  to  a  distinctly  red  color. 
Acid  soils  are  easily  corrected  by  the  use 
of  lime.  The  latter  favors  Thielavia  rot 
but  this  is  no  consideration  where  sterilized 
soil  is  used. 

HHIZOCTONIA   ROOT   ROT 

Corticium  vagum  B.  and  C. 

No  mention  is  made  in  literature  of  a 
Rhizoctonia   disease  of   sweet  peas,   al- 

1  Harris,  J.  E.,  Soil  Acidity  and  Methods  for  its  De- 
tection.   Science.     N.  S.  XL: 491-493,   1914. 


Fig.  5. — Root  Rot  caused  by  Rhizoctonia. 
Healthy  and  diseased  plants. 


Fig.  6. — Root  Rot  caused  by  Rhizoctonia. 
To  the  right  the  soil  was  inoculated 
with  the  fungus,  resulting  in  no  ger- 
mination; to  the  left,  check. 


DISEASES  IN  GREENHOUSE        99 

though  the  same  fungus  is  recorded  on 
other  hosts.  During  the  winters  of  1911 
and  1912,  it  was  found  by  the  author  on 
greenhouse  sweet  peas  from  different  lo- 
calities. Through  correspondence,  Pro- 
fessor A.  D.  Selby  reports  its  presence  in 
Ohio;  Dr.  W.  G.  Sackett,  in  Colorado;  and 
Professor  E.  C.  Stackman,  in  Minnesota. 
There  seems  no  doubt  that  the  Rhizoctonia 
root*  rot  of  sweet  peas  is  much  more  wide- 
spread than  is  reported.  The  nature  of 
the  trouble  is  unknown  to  the  growers. 
Outdoors,  Rhizoctonia  also  attacks  the  gar- 
den pea,  bean,  lettuce,  carrot,  celery,  cow 
peas,  and  a  number  of  other  hosts. 

SYMPTOMS.  Severely  infected  plants 
have  practically  no  root  system  (fig.  5)- 
In  slightly  infected  plants,  only  one  or  two 
rootlets  may  be  destroyed.  The  fungus 
produces  a  browning  effect  of  the  root  be- 
fore total  destruction  sets  in.  In  very 


ioo    DISEASES  OF  THE  SWEET  PEA 

early  stages  of  the  disease  infected  seed- 
lings are  seen  to  have  a  wilted  appearance; 
as  the  disease  progresses  they  fall  over  and 
collapse.  The  fungus  is  not  often  con- 
fined to  the  roots  alone.  It  frequently 
works  its  way  up  to  the  stem,  producing  a 
constricted  area  which  marks  it  off  from  the 
healthy  part  above.  The  fungus  being  a 
soil  organism  is  usually  introduced  with 
manure;  infection  may  take  place  at  any 
part  of  the  roots,  or  at  the  lower  end  of  the 
stem.  When  the  latter  is  the  case,  reddish 
sunken  spots  are  observed  at  the  base  of  the 
stem.  It  seems  that  Rhizoctonia  is  pri- 
marily a  seedling  disease  of  the  sweet  pea, 
although  older  plants  too  are  found  to  be 
affected  with  the  same  fungus,  but  are  not 
killed  outright  since  they  linger  for  a  con- 
siderable time  without  producing  blossoms 
of  commercial  or  ornamental  value. 


DISEASES  IN  GREENHOUSE      101 

PATHOGENICITY.  The  pathogenicity  or 
the  disease  producing  power  of  the  sweet 
pea  Rhizoctonia  may  be  readily  proven  by 
planting  disinfected  seeds  in  sterile  soil 
and  also  in  pots  which  were  inoculated 
with  a  pure  culture  of  the  fungus  (fig.  6) . 
The  best  material  is  a  culture  which  has  an 
abundance  of  sclerotia. 

The  parasite  has  two  stages — the  Rhi- 
zoctonia, and  the  sclerotial  stages.  The 
Rhizoctonia  stage  consists  of  long  and 
narrow  mycelial  branches  varying  in  color 
from  hyaline  to  reddish  brown  (fig.  7*2) . 
These  threads  are  either  imbedded  in  the 
substratum  in  which  they  grow,  or  they  are 
aerial,  depending  on  the  media  on  which 
the  fungus  is  grown.  These  mycelial 
threads  are  the  most  active  and  are  more 
concerned  in  the  parasitism  of  Rhizoc- 
tonia. The  sclerotial  stage  consists  of 


102     DISEASES  OF  THE  SWEET  PEA 

numerous  sclerotia  which  are  made  up  of 
closely  interwoven  short  barrel-shaped 
hyphae  (fig. 


FIG.  7.    a  YOUNG  hypha  OF  Rhizoctonia  FROM  SWEET  PEA. 

b   BARREL-SHAPED   hyphcg   FROM   sclcrotid  OF  THE  SAME 
FUNGUS. 

Rhizoctonia  solani  Kuhn  produces  only 
micro  or  small  sclerotia,  whereas  Corticium 
vagum  B.  and  C.  produces  macro  or  large 
sclerotia.  After  repeated  attempts  the 
Corticium  or  perfect  stage  of  the  sweet  pea 
Rhizoctonia  could  not  be  obtained  in  pure 
culture.  This  accords  with  the  findings  of 


•* 


h;  •    -^  •  ••:•   tf--   *.*••  • 
•   ^S*\afl***- 


•\  v  '  ?'•.>•..>:;'-> 

•^,  v.r  :   •  ^; 

••X  .  -    *  -  •  SjS 


Fig.  8. — Pure  culture  of  the  Sweet  Pea 
Rhizoctonia,  showing  large  and 
smaller  sclerotia  of  the  fungus. 


g.    Q._pure  culture  of   Fusarium 
lathyri,  the  cause  of  Sweet  Pea 
Wilt. 


DISEASES  IN  GREENHOUSE      103 

Shaw  1  and  Rolfs,2  who  could  not  obtain 
the  perfect  stage  on  culture  media  but 
found  it  several  times  on  the  host.  How- 
ever, as  the  sweet  pea  Rhizoctonia  pro- 
duces macro-sclerotia  (fig.  8),  and  as  al- 
ready pointed  out  by  Shaw,  the  macro- 
sclerotia  produce  the  Corticium  stage,  the 
sweet  pea  organism  is  therefore  referred  to 
as  Corticium  vagum  B.  and  C. 

PATHOLOGICAL  CONDITIONS  OF  THE 
HOST.  Practical  men,  no  doubt,  like  to 
know  what  happens  to  the  host  plant  when 
it  is  attacked  by  the  fungus.  Rhizoctonia 
when  attacking  hosts  other  than  the  sweet 
pea,  is  found  to  parasitize  the  cambium 
layer  or  growing  part  of  the  plant.  With 
the  sweet  pea,  conditions  are  somewhat 

1  Shaw,  F.  J.  F.,  The  morphology  and  parasitism  of 
Rhizoctonia.     Mem.    Dept.    Agr.    India,    Bot.    ser.    IV: 
115-153,  1912. 

2  Rolfs,    F.    M.,    Potato    failures,    a    second    report. 
Colo.  Agr.  Expt.  Station  Bui.  91,  1904. 


104    DISEASES  OF  THE  SWEET  PEA 

similar.  The  fungus  attacks  the  phloem 
or  food  tracts  and  makes  its  way  into  the 
parenchyma  cells  as  well  as  to  the  epider- 
mal cells.  The  effect  produced  is  loss  of 
turgidity,  wilting,  and  early  collapse  of 
the  host. 

Growers  should  not  fail  to  recognize 
Rhizoctonia  root  rot  in  its  initial  stage. 
To  allow  this  fungus  to  get  a  foothold 
would  mean  the  ruin  of  an  otherwise  prom- 
ising crop. 

CH^TOMIUM    ROOT    ROT 

Ch&tomium  spiroch<zte  Patt. 

In  the  autumn  of  1912,  Professor  A.  C. 
Real  of  Cornell  University  sent  me  for 
diagnosis  diseased  specimens  of  green- 
house sweet  peas.  The  trouble  was  read- 
ily located  in  the  roots.  A  fungus  was 
found  invading  the  interior  tissues  of  the 
roots,  but  no  fruiting  stage  of  any  kind  to 


DISEASES  IN  GREENHOUSE      105 

help  identify  the  fungus  could  be  dis- 
covered. Crush  cultures  were  made  at 
once  from  the  diseased  material.  Some 
forty  poured  plates  of  nutrient  agar  were 
made.  In  five  days  a  pure  culture  of  a 
fungus  appeared  in  all  the  plates  with  the 
exception  of  one,  which  showed  a  Fusa- 
rium.  The  cultures  were  watched  closely 
and  in  two  weeks  perithecia  developed. 
The  fungus  proved  to  be  an  ascomycete 
belonging  to  the  genus  Chaetomium,  and 
determined  by  Mrs.  Flora  Patterson  'as 
C.  spirocliczte  Patt.  In  mid  winter  of  that 
same  year,  more  diseased  specimens  were 
sent  in  to  my  laboratory  by  a  grower  in 
Illinois.  These  were  greenhouse  plants 
showing  the  same  symptoms  as  those  ob- 
served on  the  plants  sent  by  Professor  Beal. 
Cultures  made  from  this  material  gave  the 
typical  fungus  Chaetomium  spirochsete. 
A  search  through  the  literature  showed  that 


106    DISEASES  OF  THE  SWEET  PEA 
several  species  were  recorded  but  none 
were  stated  to  be  parasites. 

SYMPTOMS.  At  the  first  glance  Chaeto- 
mium  root  rot  is  difficult  to  tell  from 
Thielavia.  Infected  plants  lose  their 
green  color,  become  pale  and  yellow,  and 
cease  growing.  The  root  system  is  usu- 
ally found  wanting  or  partly  destroyed. 
The  disease  seems  to  be  primarily  a  seed- 
ling trouble. 

PATHOGENICITY.  The  fact  that  a  pure 
culture  of  Ch<ztomium  spiroch<zte  was  ob- 
tained from  numerous  platings  of  dis- 
eased material  from  two  different  states 
at  once  led  to  the  supposition  that  the  or- 
ganism was  the  cause  of  the  disease.  In- 
oculations with  pure  cultures  of  the  fun- 
gus into  healthy  seedlings  proved  the 
organism  to  be  a  weak  parasite,  favored 
by  an  excess  of  moisture  in  the  soil. 

THE  FUNGUS.    The  mycelium  of  the 


DISEASES  IN  GREENHOUSE      107 

fungus  is  hyaline,  closely  septate,  and 
branched  (fig.  10*2)  when  grown  in  the 
substratum  of  the  media.  The  aerial  my- 


B 

FIG.  10.    a  SHOWING  mycelium  OF  Chatomium  Spirochcete. 
b  HAIRS,     c  and  d  asci.    e  ascospores. 

celium  consists  of  long  unbranched  fila- 
ments varying  in  color  from  light  to  deep 
lemon.  The  yellow  seems  to  be  produced 
within  the  fungus  hyphae  which  later  is 
also  transmitted  to  the  media.  In  pure 
culture  the  fungus  produces  its  perithecia 


io8    DISEASES  OF  THE  SWEET  PEA 

or  fruit  bodies  in  about  two  weeks  after 
sowing.  These  perithecia  are  covered 
with  dark  hair-like  appendages.  The 
hairs  are  straight  or  coiled  at  the  apex 
and  septate  at  unequal  intervals,  and  cov- 
ered with  very  minute  pointed  warts  (fig. 
io£).  The  asci  are  very  evanescent  and 
can  only  be  seen  in  very  young  cultures 
just  as  the  perithecia  are  forming.  In  old 
cultures  the  ascus  wall  is  easily  ruptured 
so  that  it  is  difficult  to  make  out  the  ar- 
rangement of  the  ascospores  within. 
There  are  eight  ascospores  in  each  ascus 
(fig.  loc  and  d).  The  ascospore  is  apicu- 
late  (fig.  lOe)  at  both  ends.  Its  wall  is 
smooth,  light  brown  when  young  and  dark 
when  old.  It  will  germinate  readily 
in  distilled  water  or  in  any  nutrient 
broth. 

Chaetomium  root  rot  is  not  likely  to 
prove  troublesome  in  greenhouses  where 


DISEASES  IN  GREENHOUSE      109 

the  ventilation  and  the  watering  are  prop- 
erly attended  to. 

FUSARIUM    ROOT   ROT 

Fusarium  lathyri  Taub. 

There  is  no  record  in  the  mycological 
literature  of  a  Fusarium  disease  of  the 
sweet  pea.  Numerous  complaints  from 
florists  showed  that  sweet  peas  often  did 
not  grow  well  under  glass  because  of  a 
root  rot  which  developed  early  and  in  some 
cases  destroyed  the  entire  planting.  Cul- 
tures made  by  the  writer  from  infected  ma- 
terial or  from  the  infected  soil  gave  in  each 
case  a  pure  culture  of  Fusarium. 

SYMPTOMS.  The  disease  produces  a 
sudden  flagging  of  the  leaves  accompanied 
by  sudden  wilting  and  collapse  of  the  seed- 
ling. Usually  a  fair  percentage  of  the 
seeds  germinate  and  the  plants  reach  the 


no    DISEASES  OF  THE  SWEET  PEA 

height  of  about  eight  to  ten  inches  when 
they  are  attacked  by  the  fungus.  If  the 
collapsed  seedlings  are  allowed  to  remain 
on  the  ground,  the  dead  stems  will  soon  be 
covered  with  the  sickle  shaped  spores. 
Eventually  the  dead  tissue  rots  and  dis- 
integrates and  is  soon  invaded  by  small 
fruit  flies  which  now  begin  to  distribute 
the  spores  of  the  fungus  to  different  places 
in  the  same  house. 

PATHOGENICITY.  The  pathogenicity  of 
this  fungus  is  readily  proven  by  inoculat- 
ing a  pure  culture  (fig.  9)  of  the  fungus 
into  healthy  seedlings  planted  in  sterile 
pots  and  soil.  The  seeds  germinate  and 
grow  up  to  a  height  of  seven  to  eight  inches 
and  then  succumb  to  the  parasite  which 
was  artificially  introduced  into  the  soil 

(fig.  11). 

THE  FUNGUS.  The  mycelium  of  the 
fungus  is  hyaline,  branched  and  septate. 


Fig.  ii.— Fusarium  Wilt  or  Root  Rot.    At  left,  healthy 
plant;  at  right,  infected. 


DISEASES  IN  GREENHOUSE      111 

At  an  early  age  the  hyphae  begin  to  form 
chlamydospores  or  resting  spores.  These 
are  round  hyaline  bodies  often  filled  with 
oil  globules  and  are  formed  in  the  center 
of  the  hypha.  Usually  also  the  chlamydo- 
spores are  born  at  the  tip  end  of  the  hyphae 
in  chains  of  twos,  threes,  and  even  fours. 
Old  cultures  consist  largely  of  a  mass  of 
chlamydospores.  There  are  also  two  other 
types  of  spore  forms,  and  these  appear  as 
early  as  the  third  day  in  the  pure  culture. 
These  are  micro-conidia  or  small  one-celled 
spores,  and  macro-conidia  or  large  cycle- 
shaped  spores,  varying  from  two-celled  to 
four-celled.  The  usual  form  is  three- 
celled.  In  old  cultures  the  macro-conidia 
shrink  so  that  the  septa  become  slightly 
prominent.  These  old  macro-conidia  soon 
lose  their  protoplasm,  or  they  break  up, 
presenting  a  granular  appearance.  In 
young  cultures  the  outer  wall  of  the  chla- 


112     DISEASES  OF  THE  SWEET  PEA 

mydospores  is  smooth,  but  in  old  cultures 
it  becomes  slightly  warty  or  covered  with 
minute  points.  No  perfect  stage  has  been 
found  to  accompany  this  fungus,  either  on 
the  host  or  in  pure  culture. 

Fusarium  root  rot  is  a  serious  disease 
which  threatens  to  undermine  the  growing 
of  greenhouse  sweet  peas.  The  grower 
should  do  everything  possible  to  prevent 
its  introduction  into  the  house.  In  places 
where  this  disease  has  already  gained  a 
foothold,  soil  sterilization  becomes  a  nec- 
essary part  of  sweet  pea  culture  under 
glass. 

THIELAVIA   ROOT   ROT 

Thielavia  basicola  Zopf. 
In  1912,  Chittenden  *  was  asked  by  the 
National  Sweet  Pea  Society  of  England  to 
investigate  the   "streak"   disease  of  the 

1  Chittenden,  F.  J.,  Diseases  of  the  Sweet  Pea,  Sweet 
Pea  Annual:  14-24,  1912.  London. 


<- 


Fig.  12. — Root  Rot  caused  by  Thielavia. 

Roots  of  diseased  and  healthy  plants 

of  the  same  age  compared. 


DISEASES  IN  GREENHOUSE      113 

sweet  pea.  In  his  report  before  that  so- 
ciety, Chittenden  gives  an  accurate  de- 
scription of  the  "streak,"  so  that  there  can 
be  no  doubt  that  he  had  the  disease  well  in 
mind,  that  is,  he  described  it  as  a  stem  dis- 
ease. Chittenden,  however,  attributed 
"streak"  to  Thielavia  basic ola  Zopf.  In 
this  Chittenden  erred,  for  streak  has  since 
been  found  to  be  caused  by  a  bacterium. 
Massee,1  too,  made  the  same  mistake,  for 
he  also  considered  Thielavia  as  the  cause 
of  "streak."  Streak  however  is  different 
from  Thielavia  root  rot. 

SYMPTOMS.  Plants  severely  infected 
with  Thielavia  have  practically  no  root 
system,  since  the  roots  are  destroyed  by  the 
fungus  as  rapidly  as  they  are  formed  (fig. 
12) .  All  that  is  left  of  the  root  system  is 

2  Massee,  George,  A  disease  of  sweet  peas,  asters  and 
other  plants.  Roy.  Bot.  Gard.  Kew  Bui.  of  Misc.  In- 
form. No.  1:44-52,  1912,  London. 


ii4    DISEASES  OF  THE  SWEET  PEA 

a  charred  blackened  stub.  The  fungus 
sometimes  works  upon  the  stem  to  a  dis- 
tance of  two  to  three  inches  above  ground. 
It  is  probably  due  to  this  that  some  work- 
ers have  mistaken  this  disease  for  the 
"streak."  Although  their  root  system  is 
destroyed,  affected  plants  seem  to  lin- 
ger for  a  long  time.  Diseased  plants, 
however,  cease  growing,  and  maintain 
a  dwarfed  sickly  appearance  (fig.  13) . 
These  are  useless  for  any  purpose,  as  they 
fail  to  bloom  and  merely  contaminate  the 
beds  by  their  presence. 

PATHOGENICITY.  Healthy  seedlings 
may  be  readily  infected  by  placing  a  pure 
culture  of  the  fungus  in  the  soil.  In  two 
to  three  weeks  the  roots  of  the  infected 
plants  will  be  thoroughly  diseased.  Over- 
watering  does  not  seem  to  be  a  necessary 
factor  in  infection,  although  it  no  doubt 
helps  to  weaken  the  plants  and  further 


Fig.  13.— Root  Rot  caused  by  Thielavia.    A  healthy 
plant  contrasted  with  a  diseased  plant. 


DISEASES  IN  GREENHOUSE      115 

aids  the  fungus  in  its  destructive  work. 
Thielavia  basicola  also  attacks  a  number 
of  hosts  other  than  the  sweet  pea.  Pure 
cultures  of  the  fungus  obtained  from  cow- 
pea,  violets,  parsnip,  and  tobacco,  when 
inoculated  on  the  sweet  pea  will  readily 
infect  the  latter.  This  shows  that  the  dis- 
ease will  cross  from  other  hosts  to  the  sweet 
pea  and  vice  versa. 

THE  FUNGUS.  The  mycelium  of  Tkie- 
lavia  basicola  is  hyaline,  septate  and 
branched.  The  mycelium  becomes  some- 
what grayish  with  age.  Three  kinds  of 
spore  forms  are  produced — endospores, 
chlamydospores,  and  ascospores.  Endo- 
spores are  so  called  because  they  are  formed 
inside  a  special  thread  of  the  mycelium 
(fig.  14^).  This  is  the  spore  form  that 
commonly  occurs  in  pure  cultures  of  arti- 
ficial media  and  on  the  host.  The  endo- 
spore  case  is  formed  on  terminal  branches 


ii6    DISEASES  OF  THE  SWEET  PEA 


FIG.  14.  a  Endospores.  b  c  Chlamydospores  BREAKING 
UP  INTO  INDIVIDUAL  SPORES,  d  Chlamydospores  UN- 
BROKEN, f  Ascospores.  e  SINGLE  perithecium. 

with  a  somewhat  swollen  base  and  a  long 
tapering  cell.  The  endospores  are  formed 
in  the  apex  of  this  terminal  cell  and  are 
pushed  out  of  the  ruptured  end  by  the 
growth  of  the  unf  ragmented  protoplasm  of 
the  base.  They  are  hyaline,  thin  walled, 
and  oblong  to  linear  in  shape.  The  chlam- 


DISEASES  IN  GREENHOUSE      117 

ydospores  (fig.  14^  to  d)  are  thick  walled, 
dark  brown  bodies,  borne  on  the  same  my- 
celium as  the  endospores.  This  type  of 
spore  is  formed  in  great  abundance  on  the 
host  and  particularly  within  the  affected 
tissue.  The  ascospores  (fig.  14/)  are  len- 
ticular in  shape  and  are  borne  in  asci  (or 
sacs)  within  black  perithecia  (fig.  14^) . 
This  stage,  however,  has  not  been  found  on 
the  sweet  pea  or  in  pure  culture. 

Thielavia  is  perhaps  next  in  importance 
to  Fusarium  root  rot.  The  fungus  is 
often  introduced  with  manure  or  more 
commonly  with  diseased  violets,  since  this 
flower  is  profitably  grown  in  conjunction 
with  sweet  peas. 

Growers,  therefore,  cannot  be  too  care- 
ful in  trying  to  keep  out  Thielavia  from 
the  greenhouse. 


n8     DISEASES  OF  THE  SWEET  PEA 

POWDERY    MILDEW 

Microsphtzra  alni  (Waller)  Salm. 

The  sweet  pea  mildew  was  described  by 
Massee  *  as  being  prevalent  in  England. 
Erisiphe  polygoni  was  thought  to  be  the 
cause  both  of  the  sweet  pea  and  the  garden 
pea  mildew.  In  the  United  States,  Pro- 
fessor Stewart 2  was  the  first  to  record  the 
finding  of  powdery  mildew  on  sweet  peas 
in  the  United  States.  However,  Stewart 
did  not  find  the  perithecial  stage  which 
would  help  in  the  determining  of  the 
fungus. 

Powdery  mildew  is  a  very  prevalent  dis- 
ease on  greenhouse  sweet  peas,  although 
it  is  also  very  common  on  out-of-door 
plants.  The  fungus  which  causes  mildew 

1  Massee,  George,  Fungoid  diseases  of  the  sweet  pea, 
Sweet  Pea  Annual:  20-21,  1906,  London. 

2  Stewart,  F.  C.,  Notes  on  New  York  plant  diseases. 
New  York  (Geneva)  Agr.  Expt.  Station  Bui.  328:394, 
1910. 


Fig.  15. — Powdery  Mildew,  healthy  and  diseased  leaves. 

Notice  the  white  covering  of  the  affected  leaves,  due  to  the  growth 
of  the  mildew  fungus  on  the  surface  of  the  former. 


Fig.  1 6. — Germinated  sclerotia  of  the  Sweet  Pea 
Sclerotinia  which  had  wintered  outdoors. 


DISEASES  IN  GREENHOUSE      119 

grows  on  the  surface  of  the  leaves,  thus 
giving  them  the  white  powdery  appearance 
(fig.  15) .  Affected  leaves  eventually  lose 
their  green  color,  shrivel  and  fall  off  pre- 
maturely. The  perfect  stage  of  this  fun- 
gus is  found  on  fallen  and  dead  leaves. 
Powdery  mildew  is  perhaps  universally 
found  in  every  greenhouse  where  sweet 
peas  are  grown.  It  is  worse  in  over- 
watered  houses,  and  in  overheated  houses 
with  excess  of  moisture.  Powdery  mil- 
dew is  perhaps  the  easiest  disease  to  con- 
trol. 

STEM    OR   COLLAR   ROT 

Sclerotinia  libertiana  Fckl. 

Observations  seem  to  indicate  that  this 
disease  is  limited  to  sweet  peas  grown  un- 
der glass.  A  special  effort  was  made  to 
find  this  disease  outdoors,  but  without  suc- 
cess. Under  certain  conditions  unfavor- 


120     DISEASES  OF  THE  SWEET  PEA 

able  to  the  host  this  fungus  may  attack  a 
variety  of  plants  in  the  open.  That  this 
fungus  has  not  been  found  to  attack  sweet 
peas  out  of  doors  does  not  preclude  its  ap- 
pearance in  the  field  at  any  time  in  the  fu- 
ture. 

SYMPTOMS.  Collar  rot  is  usually  a 
seedling  disease  which  causes  "damping 
off."  It  is  most  severe  in  poorly  venti- 
lated houses  or  in  beds  which  are  over- 
watered  and  lack  the  proper  drainage. 
The  disease  does  its  work  quickly.  Af- 
fected plants  first  show  a  wilting  of  the 
tip  and  flagging  of  the  leaves,  and  then  the 
seedling  falls  over  and  collapses  (fig.  17) . 
The  fungus,  Sclerotinia  libertiana,  al- 
though a  soil  organism,  cannot  attack  the 
roots  of  its  host.  The  parasite  penetrates 
the  collar  of  the  stem,  completely  invad- 
ing the  inner  vessels,  thus  cutting  off  the 
upward  flow  of  water  from  the  roots  to  the 


DISEASES  IN  GREENHOUSE      121 

parts  above.  Plants  which  have  recently 
died  have  a  water  soaked  appearance,  and 
later  covered  by  a  white  weft  of  fungus 
mycelium,  and  by  sclerotia  which  appear 
irregularly  on  or  within  the  affected  stem. 

PATHOGENICITY.  The  pathogenicity  of 
this  fungus  may  be  readily  established  by 
inoculating  healthy  seedlings  with  a  pure 
culture  of  the  fungus.  The  latter  is  easily 
re-isolated  and  the  disease  produced  at 
will.  Moisture  is  the  main  factor  in  fa- 
voring infection. 

THE  FUNGUS.  Sderotinia  libertiana,  is 
a  fungus  too  well  known  to  plant  patholo- 
gists  and  even  to  practical  growers  to  re- 
quire much  description.  Under  green- 
house conditions,  the  same  fungus  causes  a 
serious  disease  on  lettuce,  cucumbers,  to- 
matoes, violets,  and  many  other  plants. 
When  grown  on  artificial  media,  there  are 
no  differences  observed  on  the  different 


122     DISEASES  OF  THE  SWEET  PEA 

strains  isolated  from  the  sweet  pea,  lettuce, 
cucumbers,  tomatoes  or  violets.  More- 
over, any  one  of  these  strains  will  produce 
a  disease  on  any  of  the  hosts  enumerated. 
When  the  sclerotia,  after  being  placed  out- 
doors in  the  cold  to  over  winter,  are  taken 
in  and  placed  on  moist  sand  kept  at  room 
temperature,  they  germinate  and  produce 
the  typical  grayish  stalks  with  their  apo- 
thecia  or  fruit  bodies  (fig.  16) .  The  latter 
contain  the  asci  in  which  are  the  ascospores 
of  the  fungus. 

Like  Thielavia  basicola,  and  because  of 
its  omnivorous  nature,  the  fungus  Sclero- 
tinia  libertiana  may  prove  a  great  draw- 
back to  the  culture  of  greenhouse  sweet 
peas.  The  parasite  is  usually  carried  with 
the  manure  or  may  be  introduced  on  other 
diseased  plants.  Failure  to  recognize  col- 
lar rot  or  carelessness  in  maintaining 


DISEASES  IN  GREENHOUSE      123 

proper  conditions  in  the  house  may  entail 
serious  losses  to  the  grower. 

ROOT    KNOT   OR    EEL   WORM 

Heterodera  radicicola  (Greef)  M tiller 

ROOT  KNOT,  (nematode  galls)  no  less 
important  than  Rhizoctonia  and  Fusarium 
root  rots,  causes  great  loss  to  greenhouse 
sweet  peas.  It  does  not,  however,  produce 
a  damping  off  in  young  seedlings.  It 
seems  very  probable,  too,  that  root  knot 
in  the  case  of  the  sweet  pea  opens  the  way 
to  the  attacks  of  Rhizoctonia  and  several 
other  root  troubles,  producing  also  the 
greatest  amount  of  damage  in  light  sandy 
soils. 

SYMPTOMS.  The  disease  is  character- 
ized by  swellings  on  the  roots.  These  are 
either  small  knots  formed  singly,  in  pairs, 
or  in  strings,  thus  giving  the  affected  root 


124  DISEASES  OF  THE  SWEET  PEA 
a  beaded  appearance;  or  else  the  swellings 
are  very  large  (fig.  19)  so  as  to  be  mistaken 
for  bacterial  nodules,  which  occur  nor- 
mally in  great  abundance.  Root  galls, 
however,  cannot  be  mistaken  for  legume 
nodules,  since  the  latter  in  the  case  of  the 
sweet  pea  are  lobed  and  are  attached  at  one 
end  (fig.  18) ;  whereas,  the  root  galls  pro- 
duce a  swelling  of  the  entire  surface  of  the 
part  affected.  Infected  plants  usually 
linger  for  a  long  time,  but  they  can  be  dis- 
tinguished by  a  thin  growth  and  yellow 
sickly  looking  leaves  and  stems. 

DISTRIBUTION.  The  eel  worm  of  the 
root  knot,  as  it  is  more  often  called,  seems 
to  be  of  wide  distribution,  being  found 
in  Europe,  Asia,  Africa,  Australia,  and 
both  North  and  South  America.  Al- 
though it  is  found  in  most  parts  of  the 
world,  there  are  many  localities  in  which 
the  pest  has  never  been  known. 


Figs.  18, 19. — Root  knot  of  Sweet  Peas,  a  root  trouble  which 
may  be  mistaken  for  the  true  legume  root  nodules. 

The  insert  cut  in  the  top  left-hand  corner  shows  the  normal  root  nodules 
of  the  Sweet  Pea  formed  by  nitrogen-fixing  bacteria. 


DISEASES  IN  GREENHOUSE      125 

LIFE  HISTORY.  The  eel  worm  is  a  very 
minute  organism  seldom  exceeding  one- 
twenty-fifth  of  an  inch  in  length,  and  since 
it  is  semi-transparent,  it  cannot  be  easily 
detected  with  the  naked  eye.  In  search- 
ing for  eel  worms,  endeavor  to  break  a  fresh 
knot.  Close  examination  will  usually  re- 
veal two  types  of  worms :  a  spindle  shaped 
worm,  the  male,  and  a  pearly  white  pear 
shaped  organism,  the  female,  firmly  em- 
bedded in  the  gall  tissue.  The  female  is 
very  prolific,  depositing  no  less  than  400 
to  500  eggs  during  her  lifetime.  The  eggs 
are  whitish  semi-transparent  bean  shaped 
bodies  and  too  small  to  be  noticed  without 
the  aid  of  a  magnifying  glass.  The  time 
which  elapses  until  the  eggs  hatch  depends 
largely  upon  weather  conditions.  With 
warm  days  the  eggs  hatch  sooner  than  in 
colder  weather.  Upon  hatching,  the 
young  larvae  either  remain  in  the  tissue  of 


126     DISEASES  OF  THE  SWEET  PEA 

the  host  plant  in  which  they  have  emerged, 
or,  as  is  more  often  the  case,  leave  the  host 
and  enter  the  soil.  This  is  the  only  period 
during  which  the  worms  move  about  to  any 
great  extent  in  the  soil,  where  they  either 
remain  for  some  length  of  time  or  immedi- 
ately penetrate  another  root  of  the  host. 
The  nematodes  in  most  cases  become  com- 
pletely buried  in  the  root  tissue,  establish- 
ing themselves  in  the  soft  cellular  struc- 
ture which  is  rich  in  food.  The  head  of 
the  worm  is  provided  with  a  boring  appa- 
ratus consisting  of  a  sharply  pointed  spear, 
located  in  the  mouth;  this  structure  not 
only  aids  it  in  getting  food  but  is  also 
valuable  in  helping  the  young  worms  to 
batter  through  the  cell  walls  before  becom- 
ing definitely  located.  The  two  sexes 
during  development  are  indistinguishable 
up  to  fifteen  or  twenty  days,  both  being 


DISEASES  IN  GREENHOUSE      127 

spindle  shaped.  In  the  molting  or  shed- 
ding of  the  skin,  there  is  a  marked  change 
in  the  case  of  the  female,  especially  in  the 
posterior  region  of  the  body,  which  no 
longer  possesses  a  tail-like  appendage. 
Fertilization  occurs  soon  after  this  molt, 
and  many  radical  changes  occur  in  the 
shape  and  structure  of  the  organization  of 
the  worm.  The  fertilized  female  in- 
creases rapidly  in  breadth  and  becomes  a 
pearly  white  flask-  or  pear-shaped  indi- 
vidual. This  creature  is  far  from  being 
worm-like  and  may  therefore  be  over- 
looked by  one  unfamiliar  with  the  life  his- 
tory of  the  eel  worm.  The  adult  male  is 
much  like  that  of  the  larvae,  being  spindle 
shaped  in  outline.  The  male  does  not 
cause  as  much  damage  to  root  tissue  as  the 
female,  and  its  purpose  in  life  seems  to  be 
only  that  of  fertilizing  the  female,  for 


128     DISEASES  OF  THE  SWEET  PEA 

after  this  function  has  been  performed  it  is 
quite  probable  that  the  male  worm  takes 
no  more  food. 

OMNIVOROUS  NATURE  OF  THE  EEL 
WORM.  Root  knot  injury  is  not  confined 
to  sweet  peas  alone.  There  are  two  hun- 
dred and  thirty-five  species  of  plants 
known  to  suffer  from  it.  This  number  in- 
cludes all  the  important  families  of  flow- 
ering plants,  gymnosperms,  and  ferns.  Of 
the  greenhouse  plants  practically  all  are 
subject  to  root  knot.  Violets,  carnations, 
chrysanthemums,  tomatoes,  cucumbers, 
and  lettuce  are  often  ruined  by  this  pest. 

Among  the  plants  which  are  not  affected 
by  eel  worm  are  the  following :  crab  grass, 
red  top,  Johnson  grass,  rye,  corn,  perennial 
rye  grass,  timothy,  and  Zinnia.  For  the 
purposes  of  greenhouse  rotation  none  of  the 
foregoing  plants  is  of  any  value.  Should 
root  knot  attack  sweet  peas  outdoors,  how- 


DISEASES  IN  GREENHOUSE      129 

ever,  especially  where  they  are  grown  on  a 
large  scale  for  seed  purposes,  rotation  of 
crops  will  have  to  be  resorted  to. 

THRIPS  1 
Heliothrips  h&morrhoidalis  Bouche 

The  damage  done  to  the  sweet  pea  by 
Thrips  is  confined  mostly  to  the  foliage. 
Thrips  feed  by  sucking  on  the  juices  of  the 
sweet  pea  plants.  New  places  and  new 
leaves  are  continually  attacked  so  that  the 
affected  parts  are  full  of  tiny  pale  spots. 
In  severe  attacks  the  spots  unite  and  form 
regular  white  blotches.  Ordinarily  it  is 
on  the  under  surface  of  the  leaves  that  the 
mites  feed,  but  when  they  become  very 
numerous  they  also  migrate  to  the  upper 
surface.  Both  sides  of  the  affected  foliage 
thus  become  covered  with  minute  drops  of 

1  For  a  more  detailed  technical  description,  see  Bull. 
64  Bur.  Ent.  U.  S.  Dept.  Agr. 


130     DISEASES  OF  THE  SWEET  PEA 

a  reddish  fluid  secreted  by  the  thrips.  As 
these  drops  dry  they  gradually  turn  black. 
As  the  attack  progresses,  the  leaves  lose 
all  their  green  color,  become  limp,  and 
drop  off. 

LIFE  HISTORY  OF  THRIPS.  An  adult 
thrip  is  about  one-twenty-fourth  of  an  inch 
in  length,  and  is  dark  brown  in  color,  with 
the  tip  of  the  body  somewhat  lighter.  The 
female  deposits  her  eggs  within  the  leaf 
tissue,  and  these  hatch  after  about  eight 
days.  The  young  larvae  feed  in  the  same 
way  as  the  adults,  but  it  is  the  young 
which  in  feeding  exude  the  reddish  drops 
previously  mentioned.  In  reaching  full 
growth  the  larvae  undergo  two  resting 
stages — prepupa  and  pupa,  during  which 
they  take  no  food  and  remain  motionless. 
Twenty  to  thirty  days  after  the  eggs  have 
hatched  the  adult  is  ready  for  reproduc- 
tion (figs.  2Oa  to  c ) . 


DISEASES  IN  GREENHOUSE      131 


FIG.     2O.      GREENHOUSE    TkfipS,    a    EGG.      &     LARVA     FIRST 
STAGE.      C   LARVA  FULL  GROWN.       (AFTER  RUSSELL.) 

Besides  the  sweet  pea,  thrips  feed  on 
lilies,  azaleas,  croton,  dahlia,  phlox,  ver- 
bena, pink,  and  ferns,  and  on  a  number  of 
other  ornamentals,  both  in  the  greenhouse 
and  in  the  open. 

RED    SPIDER 

Tetranchys  bimaculatus  Harv. 

Even  more  dangerous  to  sweet  peas  than 
mites  are  Red  Spiders  (fig.  21),  which  at- 


132    DISEASES  OF  THE  SWEET  PEA 


FIG.  21.     THE  BED  SPIDER,  ENLARGED.       (AFTER  BANKS.) 

tack  both  leaves  and  stems,  the  method  of 
attack  and  the  resulting  injury  somewhat 
resembling  that  of  mites.  However,  the 
spots  caused  by  red  spiders  are  reddish  in- 
stead of  a  pale  white. 

LIFE  HISTORY.  The  adult  female  is  usu- 
ally brick  red  in  color  and  the  male  is  red- 
dish amber.  Frequently,  however,  the 
color  of  the  red  spider  changes  according  to 
locality  and  food  plants.  The  female  lays 


DISEASES  IN  GREENHOUSE      133 

50  to  60  eggs,  depositing  about  six  per  day 
for  a  period  of  nine  days  or  so.  The  eggs 
hatch  after  about  four  days.  After  two 
days'  activity,  the  young  larvaB  pass  into 


FIG.  22.      TRIPHLEPS  INSIDIOSUS,  AN  ENEMY  OF  THE  BED 

SPIDER.    (AFTER  MCGREGOR.) 

the  pupal  or  resting  stage.  The  adults 
mate  and  the  female  is  soon  capable  of 
laying. 

In  the  greenhouse  the  red  spider  mi- 
grates from  the  tomato  and  other  plants  to 
the  sweet  pea.  The  violet  especially  is  a 


134    DISEASES  OF  THE  SWEET  PEA 

favorite  host.  Outdoors  the  red  spider 
may  attack  sweet  peas,  tomatoes,  wild  and 
cultivated  violets,  beans,  cowpeas,  dahlia, 
Jamestown  weed,  wild  blackberry,  and 
the  wild  geranium.  Although  red  spiders 
have  few  natural  enemies,  yet  the  insect 
TJiriphleps  insidiosus  (fig.  22)  frequently 
helps  to  keep  it  in  check. 


CHAPTER  V 

FIELD   DISEASES   OF   SWEET   PEAS 

As  previously  noticed,  the  diseases  which 
affect  sweet  peas  under  glass  may  also  be 
present  out-of-doors.  In  fact  the  fungi 
such  as  Thielavia,  Rhizoctonia,  Fusarium, 
Sclerotinia,  etc.,  are  all  known  to  induce, 
very  commonly,  diseases  on  plants  in  the 
field.  Indeed  their  appearance  in  the 
greenhouse  indicates  their  presence  some- 
where in  the  field  or  in  the  manure  pile, 
whence  they  are  usually  introduced  into 
the  soil.  The  spread  of  these  fungous 
pests  is  favored  by  unnatural  conditions 
which  may  occur  in  the  field  as  well  as  in 
the  greenhouse.  Continuous  foggy  and 
damp  hot  weather,  together  with  infected 
135 


136    DISEASES  OF  THE  SWEET  PEA 

soils,  will  naturally  cause  loss  and  disease. 
Thielavia  root  rot  commonly  found  in  the 
greenhouse  produces  a  similar  disease  on 
sweet  peas  in  the  field.  In  the  latter  case 
it  assumes  greater  economic  importance, 
especially  on  trial  grounds.  Root  knot 
has  so  far  been  encountered  only  on  green- 
house sweet  peas.  It  will  doubtless  be 
found  in  the  field,  however,  before  long. 
The  same  is  also  true  for  the  Rhizoctonia 
root  rot,  the  Fusarium  root  rot,  and  the 
Sclerotinia  collar  rot.  Growers  of  sweet 
peas  on  a  large  scale  for  seed  or  for  orna- 
mental purposes  should  be  on  their  guard 
to  prevent  the  introduction  of  these  trou- 
bles into  their  soils.  It  is  much  easier  to 
prevent  infection  than  to  eradicate  a  dis- 
ease that  has  once  gained  a  strong  foot- 
hold. Powdery  mildew,  a  common  leaf 
trouble  in  the  greenhouse,  is  found  also 
outdoors  to  some  extent.  On  irrigated 


FIELD  DISEASES  137 

sweet  peas  it  assumes  the  nature  of  an  epi- 
demic and  may  cause  death  of  all  the 
foliage. 

ANTHRACNOSE 

Glomerella  rufomaculans  (Berk.)  V.  Sck. 
and  Sp. 

Of  all  field  diseases  Anthracnose  is  per- 
haps the  most  dreaded  in  the  United 
States  because  of  the  great  losses  it  occa- 
sions. Anthracnose  on  the  sweet  pea  may 
exist  wherever  apples  are  suffering  from 
bitter  rot,  for,  as  the  writer  has  definitely 
proven,  bitter  rot  of  apples  and  anthrac- 
nose  of  sweet  peas  are  caused  by  the  same 
fungus,  Glomerella  rufomaculans. 

SYMPTOMS.  The  symptoms  of  anthrac- 
nose  are  varied.  Sometimes  it  is  mani- 
fested by  a  wilting  or  dying  of  the  tips 
(fig.  23)  which  become  whitish  and  brittle 


138     DISEASES  OF  THE  SWEET  PEA 

and  readily  break  off.  At  other  times  the 
injury  extends  further  down  and  involves 
the  entire  branch.  On  the  leaves  the  dis- 
ease starts  as  whitish  spots,  which  enlarge 
until  all  the  green  gradually  fades  en- 
tirely, hence  causing  death  (fig.  24) . 
Such  infected  leaves  become  brittle  and 
soon  drop  off.  Examination  of  an  in- 
fected leaf  with  a  hand  lens  shows  that  it 
is  peppered  with  minute  salmon  colored 
pustules.  At  the  time  of  blossoming  the 
fungus  also  attacks  the  peduncle  at  the 
point  of  union  with  the  buds,  producing  a 
bud  blight;  or  the  fungus  attacks  both  the 
flower  bud  and  the  peduncle,  in  which  case 
both  dry  up  but  do  not  fall  off.  The  most 
easily  distinguishable  symptoms  of  this 
disease  are  on  the  seed  pods.  Infected 
pods  lose  their  green  color,  become  shriv- 
eled, and  are  soon  covered  with  salmon 
colored  patches  which  frequently  attract 


Fig.  23. — Anthracnose  Disease  of  Sweet  Pea  on  stem 
and  peduncles. 


Fig.  24. — Anthracnose  Disease  affecting  Sweet 
Pea  leaf. 


FIELD  DISEASES  139 

attention.  The  disease  is  often  worse 
where  green  Aphids  are  very  active.  In 
this  case  the  older  vines  may  be  affected  at 
any  point.  Very  often,  too,  the  harder 
vines  may  escape  the  disease  which  attacks 
the  thin  blades  on  each  side.  Here  the  af- 
fected blades  become  white  and  dry  and 
break  at  handling.  If  not  disturbed  they 
become  covered  with  pink  pustules  or 
fruits  of  the  parasitic  organism. 

The  anthracnose,  like  the  "streak,"  is  of 
great  economic  importance.  When  once 
introduced  into  a  field  the  disease  spreads 
rapidly,  often  destroying  the  entire  crop. 
Unlike  "streak,"  the  anthracnose  may  at- 
tack young  seedlings,  a  condition  some- 
times found  in  the  greenhouse.  In  the 
field,  the  disease  starts  about  July  i ,  when 
the  plants  are  in  full  bloom  and  in  the 
prime  of  beauty.  This  is  also  the  time 
when  the  bitter  rot  disease  of  the  apple 


140    DISEASES  OF  THE  SWEET  PEA 

(fig .  25)  makes  its  appearance  in  the 
orchard.  The  fungus  is  carried  over  win- 
ter on  cankered  limbs  and  mummied  fruits 
of  diseased  apples  or  on  the  diseased  pods 
of  the  sweet  pea  as  well  as  in  the  soil. 

MODE  OF  INFECTION  AND  PERIOD  OF  IN- 
CUBATION. The  anthracnose  of  the  sweet 
pea  is  mainly  a  disease  of  the  tender  parts 
of  the  plant.  Infection  usually  starts  first 
at  the  tips,  although,  as  previously  shown, 
the  fungus  may  attack  the  older  parts  of 
the  plant  once  they  have  been  injured  by 
green  Aphids  or  by  red  spiders.  The 
spores  of  the  parasite  usually  germinate  in 
from  six  to  twenty-four  hours,  according 
to  the  amount  of  moisture  present.  The 
germ  tubes  enter  the  host  by  breaking 
through  the  epidermal  cells  of  either  leaf 
or  stem. 

The  period  of  incubation  varies  from 
three  to  five  days,  according  to  the  amount 


Fig.  25. — Bitter  Rot  of  Apple  induced  by  the  same  fungus 

which  causes  Anthracnose  of  the  Sweet  Pea, 

viz.  Glomerella  rufomaculans. 


Fig.  26. — Sweet  Pea  Mosaic,  showing,  a.  leaflet 
affected  with  the  disease,  b.  healthy. 


FIELD  DISEASES  141 

of  moisture  in  the  atmosphere.  The 
acervuli  or  spore  pustules  appear  within 
five  days  after  wilting  begins,  unless  the 
weather  is  dry,  when  they  may  not  appear 
until  considerably  later. 

MOSAIC   DISEASE   OF   THE   SWEET    PEA 

Sweet  Pea  Mosaic  is  a  serious  disease. 
It  greatly  checks  greenhouse  peas  and  is 
equally  injurious  to  sweet  peas  grown  out- 
of-doors.  Although  the  cause  of  the 
trouble  is  not  as  yet  known,  nevertheless 
all  indications  tend  to  show  that  it  is  in- 
duced by  a  definite  pathogenic  organism. 
The  same  or  a  similar  mosaic  is  known  to 
attack  a  number  of  plants  such  as  tobacco, 
egg  plant,  pepper,  tomatoes,  and  clovers. 
Its  occurrence  on  the  sweet  pea  has  been  re- 
corded only  by  the  author  l  though  it  has 

1  Taubenhaus,  J.  J.,  Present  knowledge  of  sweet  pea 
diseases.  Florist  Exchange  34:  108-110,  1912. 


142    DISEASES  OF  THE  SWEET  PEA 

probably  been  seen  by  a  number  of  grow- 
ers. 

SYMPTOMS.  Mosaic  is  readily  distin- 
guishable by  a  yellow  dotting  or  mottling 
of  the  leaf,  presenting  in  some  instances 
a  beautiful  mosaic  structure,  whence  its 
name  (fig.  26) .  Affected  leaves  linger  for 
a  time  but  they  eventually  lose  all  their 
chlorophyll  and  soon  drop  off.  Another 
symptom  of  this  disease  is  a  curling  of 
leaves  (fig.  27)  resembling  the  curling  in- 
duced by  the  green  Aphids,  but  in  this 
case  the  insects  have  no  association  with 
it.  The  disease  makes  its  appearance  after 
the  seedlings  are  from  two  to  three  weeks 
old.  Often,  the  trouble  is  so  serious  and 
the  curling  so  pronounced  that  the  plants 
thus  affected  cannot  make  any  headway 
and  remain  dwarfed.  An  attempt  is  made 
by  these  curled  plants  to  produce  a  few 
flowers,  but  the  latter  are  borne  on  very 


Fig.  27. — Mosaic  Disease  causing  dwarfing 

of  the  plant  and  a  rolling  of  the  tip 

leaves. 


FIELD  DISEASES  143 

short  peduncles  as  compared  with  the  long 
peduncles  of  healthy  plants  of  the  same  va- 
riety. Frequently,  however,  the  affected 
plants  outgrow  the  disease  entirely,  and 
thus  a  distinct  line  of  demarcation  is  ob- 
served between  the  previously  diseased 
part  and  the  healthy  part  of  the  new 
growth  (fig.  28) .  In  rare  cases,  infected 
plants  seem  to  thrive  in  spite  of  the  dis- 
ease. Such  plants  should  be  selected  for 
the  purpose  of  breeding  resistant  strains. 
PATHOGENICITY.  Like  peach  yellows 
and  the  mosaic  disease  of  tobacco  and 
tomato,  mosaic  of  the  sweet  pea  can  be 
reproduced  by  puncturing  with  a  sterile 
needle  from  the  diseased  leaf  into  a  healthy 
one.  As  yet  it  has  not  been  possible  to 
find  an  organism  associated  with  the  dis- 
ease. Nevertheless  the  disease  is  conta- 
gious. It  takes  from  ten  to  fifteen  days  for 
the  disease  to  appear  when  artificial  inocu- 


144    DISEASES  OF  THE  SWEET  PEA 

lation  is  carried  out.  The  symptoms  pro- 
duced in  artificially  inoculated  plants  are 
similar  to  those  in  the  field. 

STREAK   DISEASE 

Bacillus  lathyri  Manns  and  Taub. 

Streak  is  the  only  bacterial  disease 
which  affects  this  plant  and  no  disease 
of  the  sweet  pea  is  so  little  known  to 
the  growers.  The  attention  of  Professor 
Manns  and  the  author  was  called  to  it 
in  the  course  of  our  investigations,  that 
is  to  say,  only  about  three  years  ago. 
It  probably  has  existed,  however,  a  long 
time  in  this  country,  since  it  attacks  so 
many  other  members  of  the  legume  family, 
the  red  clovers  particularly,  upon  which 
it  causes  trouble  of  considerable  economic 
importance.  In  England  this  disease  is 
ruining  the  sweet  pea  crop  every  year.  In 
this  country  it  has  gained  a  strong  foothold 


Fig.  28. — Mosaic  Disease,  shewing  where  the 
plant  has  outgrown  the  trouble. 

x  indicates  the  area  where  the  disease  has  ceased 
activity. 


FIELD  DISEASES  145 

and  it  is  to  be  found  wherever  clovers  are 
grown. 

SYMPTOMS.  Like  the  bacteriosis  of  the 
bean,  streak  makes  its  appearance  in  the 
season  of  heavy  dew.  On  the  sweet  pea 
the  disease  usually  appears  just  as  the 
plants  begin  to  bloom;  it  is  manifested  by 
light  reddish  brown  to  dark  brown  spots 
and  streaks  (the  older  almost  purple) 
along  the  stems,  having  their  origin  usu- 
ally near  the  ground,  which  indicates  dis- 
tribution by  spattering  rain  and  infection 
through  the  stomata  or  through  insect  in- 
jury. The  disease  becomes  distributed 
quickly  over  the  mature  stems  until  the 
cambium  and  deeper  tissues  are  destroyed 
in  continuous  areas,  and  the  plant  dies 
prematurely.  From  the  stem  the  disease 
spreads  to  the  petioles,  flowers,  peduncles, 
and  pods,  the  symptoms  in  these  cases  be- 
ing similar  to  those  on  the  stems.  On  the 


146    DISEASES  OF  THE  SWEET  PEA 

leaves,  however,  the  disease  appears  as 
small  circular  spots,  which  gradually  coal- 
esce and  eventually  involve  the  entire  leaf, 
which  when  killed  presents  a  dark  brown- 
ish appearance. 

PATHOGENICITY.  The  pathogenicity  of 
the  causative  organism  may  be  proven  by 
diluting  a  pure  culture  of  the  organism  in 
sterile  water  and  by  spraying  it  on  the 
healthy  plants  with  an  atomizer.  This  is 
done  in  the  evening  when  the  temperature 
is  cooler  and  there  is  less  chance  for  evapo- 
ration of  the  infectious  liquid  which  is  ap- 
plied. The  disease  makes  its  appearance 
from  seven  to  ten  days  after  artificial  in- 
fection and  the  symptoms  are  similar  to 
those  produced  in  nature.  The  organism 
may  be  re-isolated  from  the  artificially  in- 
fected plants  and  the  disease  induced  again 
at  will  on  healthy  plants,  in  each  case  the 
uninf ected  check  plants  remaining  healthy. 


FIELD  DISEASES  147 

Natural  or  artificial  infection  can  only 
take  place  on  mature  plants  which  have 
started  to  bloom.  All  attempts  to  inocu- 
late plants  in  all  stages  of  growth  previous 
to  the  blooming  period  have  failed.  It 
seems  that  the  host  previous  to  blooming 
possesses  certain  protective  properties 
which  inhibit  the  growth  of  the  parasite. 
The  disease  in  the  field  does  not  make  its 
appearance  until  the  plants  have  started 
to  bloom. 

Over  1,500  plate  cultures  of  incipient  or 
young  lesions  were  made  from  the  sweet 
pea  and  clover.  The  organism  may  almost 
invariably  be  taken  in  pure  cultures  from 
the  young  lesions  in  the  stems  of  sweet 
peas  when  the  surface  is  properly  steril- 
ized. The  parasite  is  a  yellow  organism 
which  will  grow  luxuriantly  upon  any 
nutrient  media  containing  sugars.  On 
standard  nutrient  glucose  agar  the  colonies 


148     DISEASES  OF  THE  SWEET  PEA 

appear  within  24  to  36  hours.  The  center 
becomes  granular  and  the  colonies  have  a 
marked  tendency  to  become  stellate  or  au- 
riculate  (fig.  29) . 

Morphological  studies  show  the  organ- 
ism to  be  a  comparatively  small  rod-shaped 
bacillus,  which  in  fresh  cultures  is  rarely 
found  in  chains,  and  seldom  united  in  twos 
or  fours.  The  flagella  or  appendages  of 
the  organism  are  not  easily  demonstrated; 
they  are  shed  so  readily  that  usually  not 
more  than  two  to  five  may  be  found  in 
stained  material  and  these  are  generally 
quite  short.  However,  when  the  proper 
material  is  selected,  carefully  fixed  and 
stained,  the  flagella  may  be  demonstrated 
to  be  very  long  and  delicate,  and  to  be 
from  8  to  12  in  number  and  well  dis- 
tributed peritrichially. 


Fig.  29.— Pure  culture  of  the  streak 
organism,  Bacillus  lathyri. 


Fig.  30. — Sweet  Pea  aphis  parasitized  by  a  fungus, 
Empusa  aphidis. 


CHAPTER  VI 

DISEASES    NOT    YET    KNOWN    TO    ATTACK 
SWEET    PEAS    IN    AMERICA 

IN  an  article  in  the  Sweet  Pea  Annual, 
Massee  *  describes  a  pea  blight  and  a  pea 
spot,  which  as  far  as  is  known  have  not 
yet  made  their  appearance  in  this  country. 

.     PEA    BLIGHT 

Peronospora  trifoliorum  DeBy. 

According  to  Massee,  this  disease  is  very 
destructive  to  peas,  lupines,  and  most 
other  plants  of  the  pea  family.  The  dis- 
ease may  appear  and  spread  quickly  when 
the  plants  are  only  a  few  inches  high,  or 
it  may  attack  older  plants.  In  dry 

1  Massee,    G.,    Fungoid    diseases    of  the    sweet    pea. 
Sweet  Pea  Annual,  pp.  20-21,  1906,  London. 
149 


150    DISEASES  OF  THE  SWEET  PEA 

weather  the  mycelium  of  the  fungus 
spreads  in  the  tissue  throughout  the  leaf, 
which  soon  assumes  a  sickly  yellow-green 
color,  and  finally  bleaches,  shrivels,  and 
dies  without  showing  any  or  only  a  small 
amount  of  the  mold  on  the  surface.  In 
damp  cloudy  weather  infected  leaves  show 
yellow  patches,  which  soon  become  covered 
on  one  or  both  surfaces  with  a  very  delicate 
grayish  lilac  colored  mold. 

The  summer  spores  are  produced  on  the 
leaves  or  on  any  other  part  of  the  host. 
The  winter  or  resting  spores  are  imbedded 
in  the  tissue  of  the  host  that  has  been  pre- 
viously killed  by  the  fungus.  The  resting 
spores  have  a  very  thick  smooth  brown 
wall. 

Peronospora  mem  also  produces  a  dis- 
ease on  sweet  peas. 


DISEASES  NOT  YET  KNOWN     151 

PEA    SPOT 

Ascochyta  pisi  Lib. 

According  to  Massee,  this  disease  attacks 
sweet  peas,  French  beans  and  several  other 
leguminous  crops.  The  first  indications  of 
disease  is  the  appearance  on  the  pods  of 
pale  green  spots  of  variable  size  and  irreg- 
ular shape.  These  blotches  continue  to  in- 
crease in  size  for  some  time  and  eventually 
become  whitish,  bordered  with  a  dark  line, 
and  the  surface  is  studded  with  minute 
black  points  which  are  the  pycnidia  or  spore 
sacks  of  the  fungus. 

It  should  be  remembered  that  both  Asco- 
chyta  pisi  and  Peronospora  trifoliorum  are 
fungi  very  prevalent  on  other  hosts  in  this 
country.  It  is  only  a  matter  of  time  until 
these  parasites  will  be  found  to  attack 
sweet  peas.  Growers,  therefore,  should  be 
on  their  guard  against  these  two  troubles. 


CHAPTER  VII 

INSECT   PESTS 
THE   SWEET    PEA   APHIS 

Macrosiphum  pisi  Kalt. 

OF  all  the  sweet  pea  insects,  not  one 
perhaps  rivals  in  economic  importance  the 
green  aphis.  Specimens  were  submitted 
to  Professor  Chittenden  of  the  United 
States  Department  of  Agriculture,  who 
identified  them  as  M.  pisi  Kalt.  Since 
this  pest  is  the  same  which  also  attacks  the 
garden  and  field  pea  we  will  quote  in  part 
Professor  Chittenden.1 

DESCRIPTION.  "The  pea  aphis  is  one  of 
unusual  size  among  those  found  infesting 

1  Chittenden,  F.  H.,  The  pea  aphis  (Macrosiphum 
pisi  Kalt.)  U.  S.  Dept.  Agr.  Bur.  of  Entomol.  Circ.  43 
Second  Edition,  1909. 

152 


INSECT  PESTS 


153 


gardens,  and  the  largest  of  the  green 
species  which  attacks  the  pea  and  related 
plants  (fig.  31  a  to  e)  .  The  general  color 


FIG.  31.  SWEET  PEA  Aphis,  Q,  WINGED  FEMALE,  b  SAME 
FROM  SIDE  WITH  WINGS  FOLDED  IN  NATURAL  POSITION, 
AS  WHEN  FEEDING.  C  ApterOUS  FEMALE.  rf  NYMPH 
IN  LAST  STAGE.  (AFTER  CHITTENDEN.) 

of  the  insect  is  uniform  pea  green,  the  same 
color  as  the  insect's  favorite  food  plant. 
The  eyes  are  prominent  and  reddish  brown 
in  color.  The  antennae  are  lighter  than  the 
body  and  the  tubercules  prominent.  The 
legs  are  long  and  conspicuous. 


154    DISEASES  OF  THE  SWEET  PEA 

"Like  the  gipsy  moth,  the  pea  aphis  seems 
to  have  been  present  in  this  country  for 
about  twenty-five  years  before  it  became  a 
pest.  It  is  now  found  practically  wher- 
ever the  garden  pea  and  the  sweet  pea  are 
grown,  causing  much  injury  to  both  hosts. 

'The  reasons  why  the  species  has  be- 
come so  troublesome  a  pest  are  many: 
First,  because  of  its  ravages  to  a  crop  hith- 
erto little  troubled  by  insects  except  the 
pea  weevil,  which  has  always  been  present 
in  gardens  and  fields  and  has  come  to  be 
looked  upon  as  a  necessary  evil.  Second, 
it  is  a  species  never  before  noticed  so  far 
as  records  go  as  having  been  destructive  to 
peas  of  any  kind  in  this  country.  Third, 
because  of  the  great  difficulty  in  keeping  it 
in  check. 

"Although  garden  and  field  peas  are  the 
crops  most  injured  by  this  pest,  sweet  peas 
and  red  and  crimson  clover,  as  well  as 


INSECT  PESTS  155 

vetches,  are  affected.  Attacks  begin  on 
the  young  pea  vines;  the  lice'  gather  in 
clusters  at  first  under  and  within  the  termi- 
nals, and  as  the  leaves  become  covered  they 
attack  also  the  stems  and  by  their  numbers 
and  veracity  sap  the  life  of  the  plant. 
Whole  areas  of  vines  are  seen  covered  with 
the  aphis." 

How  THE  APHIDS  MULTIPLY.  The 
"lice"  spend  the  winter  in  the  egg  stage. 
When  the  young  sweet  pea  seedlings  ap- 
pear in  the  spring  the  lice  hatch  from  the 
eggs,  and  instead  of  being  partly  males 
and  partly  females,  all  are  females,  known 
as  stem  mothers.  These  without  the  in- 
tervention of  the  male  give  birth  to  a  sec- 
ond generation,  all  of  which  are  likewise 
females.  These  females  in  turn  give  birth 
to  a  third  generation  of  females  and  in  this 
manner  a  large  number  of  successive  gen- 
erations are  produced,  in  none  of  which 


156    DISEASES  OF  THE  SWEET  PEA 


FIG.  32.  SHOWING  HOW  APHIDS  FEED  AND  THE  NECESSITY 
OF  A  CONTACT  SPRAY  TO  KEEP  IT  IN  CHECK.  (COURTESY 
OF  THE  KENTUCKY  TOBACCO  PRODUCTS  CO.) 

do  any  males  occur.  This  form  of  repro- 
duction without  the  intervention  of  the 
male  is  known  as  parthenogenesis.  On  the 
approach  of  cool  fall  weather  a  generation 


INSECT  PESTS  157 

composed  of  both  males  and  females  are 
produced,  the  sexes  mate,  and  eggs  are 
laid  which  pass  the  winter  on  dead  stems 
or  in  the  ground.  According  to  present 
knowledge  the  eggs  hibernate  on  clover  or 
vetch.  The  sweet  pea  aphis  derives  its 
food  by  sucking  on  the  plant  juices  (fig. 

32). 

The  sweet  pea  aphis  is  not  only  a  pest 
by  itself,  but  it  also  aids  in  carrying  the 
virus  of  mosaic  from  plant  to  plant. 
Moreover,  plants  which  have  their  juices 
constantly  depleted  by  numerous  sucking 
aphids  are  thereby  weakened  and  easily 
fall  the  prey  to  diseases,  especially  streak 
and  anthracnose.  If  the  green  aphis  could 
be  successfully  controlled,  nearly  80  per 
cent  of  the  other  troubles  would  be  pre- 
vented from  getting  a  start. 

Greenhouse  sweet  peas  are  not  exempt 
from  the  attacks  of  the  aphis.  In  the 


158     DISEASES  OF  THE  SWEET  PEA 

greenhouse,  too,  the  prevalence  of  the  aphis 
is  always  correlated  with  an  abundance  of 
mosaic,  as  well  as  with  weak  spindly 
plants. 

The  sweet  pea  aphis  is  very  prolific.  It 
is  estimated  that  each  individual  if  al- 
lowed full  sway  would  be  the  progenitor 
of  423,912  aphids  in  one  season.  These 
lice,  however,  are  fortunately  kept  in  check 
by  natural  enemies.  The  list  of  insects 
known  to  feed  on  the  sweet  pea  aphid 
includes  seven  species  of  lady  beetles,  three 
species  of  Syrphus  or  lace  wing  fly,  a  sol- 
dier beetle,  and  a  few  minute  four  winged 
Hymenopterous  parasites. 

LADY  BEETLES.  Hippodamia  converg- 
ens.  It  behooves  every  grower  to  learn  to 
recognize  this  friendly  insect.  Its  eggs 
are  laid  in  clusters,  found  everywhere  on 
board  fences  or  on  trees.  The  eggs  are 
small,  salmon  color,  and  pointed  at  both 


INSECT  PESTS  159 

ends.  The  larvae  as  they  emerge  from  the 
eggs  soon  begin  to  feed  on  very  small  in- 
sects. Their  body  is  long,  very  rough, 
hairy,  and  dark  with  red  or  yellow  mark- 
ings on  its  back.  As  soon  as  they  reach 
maturity  they  attach  themselves  by  the 
tail  end  to  some  twig  and  there  pupate. 
From  this  stage  emerges  the  adult  lady 
beetle.  The  sexes  mate  and  the  females 
lay  the  eggs  which  are  to  begin  a  new  life 
cycle  (fig.  33  a  toe). 


FIG.   33.      THE  CONVERGENT  LADY  BEETLE    (Hippodamia  COH- 

vergens)    AN   ENEMY   OF  THE   SWEET   PEA  APHIS,    a 

ADULT  BEETLE.      b    PUPA.      C   LARVA.       (AFTER  CHITTEN- 
DEN.) 


160     DISEASES  OF  THE  SWEET  PEA 

SYRPHID  FLIES.  Syrphus  ribesii.  In 
company  with  the  plant  lice  are  seen 
greenish,  flat  sticky  looking  "worms," 


FIG.  34.     SYRPHID  FLY,  Syrphus  Americanus,  WHOSE  LARVA 

FEEDS  ON  THE  SPRING  GREEN  APHIS  AND  ALSO  ON  THE 
SWEET  PEA  APHIS,  a  FEMALE  FLY.  b  SECOND  ABDOM- 
INAL SEGMENT  OF  MALE.  (AFTER  WEBSTER  AND  PHIL- 
IPS.) 

which  are  pointed  at  one  end  and  seem 
to  have  no  distinct  head,  eyes,  or  legs. 
These  are  larvae  or  maggots  of  a  two- 
winged  fly  commonly  known  as  Syrphid 
or  Flower  Fly.  The  maggots  obtain 
their  food  by  puncturing  the  body  wall  of 


INSECT  PESTS  161 

the  aphid  and  by  sucking  out  its  con- 
tent. When  the  maggot  is  full  grown 
it  seeks  some  sheltered  spot  where  it 
pupates  and  becomes  transformed  into  the 
adult  fly.  The  adults  are  dark,  with 
transverse  yellow  bands  across  the  abdo- 
men (fig.  34  a  and  b).  They  are  swift 
fliers  and  are  often  mistaken  for  bees. 
They  feed  on  the  nectar  of  flowers  and  be- 
cause of  this  habit  are  often  called  Flower 
or  Honey  Flies.  On  hot  days  they  are 
very  numerous  and  are  called  Sweat  Flies. 
They  lay  their  eggs  on  vines  attacked  by 
the  aphids. 

GREEN  LACE  WING.  Chrysopa  calif  or- 
nica.  This  insect  is  called  Aphis  Lion  be- 
cause of  its  destructiveness  to  all  green 
plant  lice.  The  larvae  of  these  beneficial 
flies  are  provided  with  two  long  curved 
mandibles  upon  which  the  aphids  are  held 
prisoners  until  they  are  sucked  dry.  They 


162     DISEASES  OF  THE  SWEET  PEA 


PIG.  35.  GREEN  LACE  FLY  (ChrySOphd  OCUldto)  AN  ENEMY 
OF  THE  SWEET  PEA  APHIS,  O  EGGS.  &  FULL  GROWN 
LARVA.  C  FOOT  OF  SAME,  d  LARVA  DEVOURING  AN 
INSECT,  e  COCOON,  f  ADULT  INSECT,  g  HEAD  OF  SAME. 
h  ADULT  NATURAL  SIZE.  (AFTER  MARLATT.) 

are  then  released  and  others  caught  and 
destroyed  in  a  similar  way  (fig.  35  a  to  h) . 
APHIDUIS.  Of  still  greater  importance  in 
the  natural  control  of  the  sweet  pea  aphis, 
is  the  parasite  known  as  Aphiduis  testa- 
ceipes  (fig.  36) .  The  adult  female  of  this 
fly  possesses  a  long  sharp  pointed  ovipos- 
itor which  pierces  the  body  wall  of  the 


INSECT  PESTS  163 

louse  depositing  her  eggs  within  its  tissue. 
When  the  female  Aphiduis  comes  in  con- 
tact with  an  aphis,  she  quickly  thrusts  her 
abdomen  beneath  its  thorax  and  head,  giv- 
ing the  aphis  a  quick  stab,  and  deposits  her 


FIG.  36.    Aphiduis  testaceipes  OVIPOSITING  IN  THE  BODY  OF 

AN  APHIS.      ENLARGED.       (AFTER  WEBSTER.) 

eggs  in  its  body.  After  being  stung  by  her 
enemy,  the  aphis  kicks  up  the  posterior 
part  of  the  abdomen  as  though  in  pain. 
It  is  probable  that  only  one  egg  is  depos- 
ited within  the  body  of  each  attacked  aphid. 
The  egg  upon  hatching  gives  birth  to  a 
small  legless  larva  which  begins  at  once  to 
feed  upon  the  interior  vital  parts  of  the 
louse.  The  latter  soon  becomes  less  active, 


164    DISEASES  OF  THE  SWEET  PEA 

loses  its  natural  color,  then  turns  gray  and 
dies,  remaining  attached  to  the  part  of  the 
plant  upon  which  it  has  been  feeding. 
When  the  larva  is  fully  developed  it 
pupates  and  cuts  a  circular  hole  on  the 
top  of  the  body  of  the  now  "mummied" 
aphis,  emerging  as  a  winged  insect  to  at- 
tack other  living  aphids  in  the  same  way 
as  its  mother.  The  circular  hole  cut  by 
the  escaped  parasites  is  always  a  sure  sign 
of  the  presence  of  these  beneficial  in- 
sects. 

In  the  summer  of  1911,  the  author  no- 
ticed that  Aphiduis  testaceipes  alone  de- 
stroyed and  kept  in  check  what  seemed  an 
epidemic  of  the  sweet  pea  aphis.  On  the 
other  hand,  in  the  summer  season  of  1912, 
this  beneficial  parasite  was  rather  scarce. 
It  is,  therefore,  interesting  to  know  the  con- 
ditions which  determine  its  presence  or 
absence.  The  following  are  observations 


INSECT  PESTS  165 

recorded  by  Webster  and  Philips :  *  The 
dispersion  of  Aphiduis  may  be  accom- 
plished by  the  larvae  in  the  bodies  of  the 
winged  aphids  whence  it  is  carried  from 
place  to  place  and  also  by  the  wind. 
While  the  young  larvae  are  within  the 
body  of  the  aphis  they  are  not  easily  de- 
tected. It  is  only  when  the  larva  becomes 
nearly  full  grown  that  it  may  be  detected, 
and  then  only  by  an  expert  observer. 
There  may  be  millions  of  larvae  of  Aphiduis 
in  a  field  and  yet  present  no  visible  indi- 
cation of  their  presence.  A  few  warm  days 
bring  about  their  final  development, 
whereupon  the  presence  of  the  leathery 
brown  bodies  of  the  parasitized  aphids  be- 
gin to  attract  the  attention.  Climatic  con- 
ditions are  important  factors  in  determin- 
ing the  abundance  of  Aphiduis. 

1  Webster,  F.  M.,  and  Philips,  W.  J.,  The  spring  grain 
aphis  or  "green  bug."  U.  S.  Dept.  Agr.  Bur.  Entom. 
Bull,  no,  1912. 


i66     DISEASES  OF  THE  SWEET  PEA 

APHELINUS.  Another  insect  which  par- 
asitizes the  sweet  pea  aphids  is  Aphelinus 
nigritus,  a  parasite  also  known  to  attack  a 
number  of  other  green  plant  lice  (fig.  37) . 


FIG.  37.    Aphelinus  Nigritus;  A  PARASITE  OF  THE  SWEET 
PEA  Aphis.     (AFTER  WEBSTER  AND  PHILIPS.) 

This  insect,  however,  is  not  so  active  as 
the  Aphiduis  previously  mentioned. 

FUNGOUS  PESTS.  The  fungi  which  help 
to  destroy  the  sweet  pea  aphids  are  not 
as  yet  well  known.  Empusa  aphidis  (fig. 
30)  is  the  only  fungus  which  has  received 
some  attention  and  study.  The  others  re- 


INSECT  PESTS  167 

main  to  be  investigated.  The  develop- 
ment of  Empusa  aphidis  depends  upon 
rather  warm,  humid  weather  for  its  spread 
and  is  retarded  by  drought.  This  fungus 
was  found  fairly  active  during  the  sum- 
mer of  1912.  It  is  possible  to  cultivate 
the  fungus  artificially  and  it  may  be  used 
to  inoculate  broadcast  the  aphids  in  the 
field. 

THE  TWELVE-SPOTTED  CUCUMBER  BEETLE 

Diabrotica  12  punctata  Oliv. 

The  larva  of  this  insect  feeds  on  roots 
and  stalks  of  corn  and  on  a  number  of 
other  plants  but  as  far  as  is  known  does  not 
feed  on  roots  and  stems  of  sweet  peas.  It 
is  the  adult  beetle  of  this  insect  that  is 
troublesome  to  outdoor  sweet  peas.  The 
beetle  is  one  of  the  earliest  pests  seen  to 
feed  on  the  plants,  as  soon  indeed  as  they 
are  no  more  than  six  inches  high.  The  in- 


168     DISEASES  OF  THE  SWEET  PEA 

jury  is  confined  to  the  leaves,  where  it  ex- 
tends over  large  areas.  The  beetle  is  often 
known  as  the  12  spotted  cucumber  beetle, 
the  color  of  its  body  being  yellowish  green 
and  its  wing  covers  marked  by  twelve 
black  dots.  Besides  the  sweet  pea,  the 
adult  beetle  also  feeds  on  cucumber, 
squash,  and  melon  blossoms.  It  also  feeds 
on  alfalfa,  clover,  cotton,  rye,  and  to- 
bacco. This  species  is  abundant  in  the 
Southern  states;  although  its  range  in  the 
North  is  also  very  wide.  Despite  its  being 
an  early  species,  the  beetle  is  also  found 
feeding  on  sweet  peas  which  have  long 
passed  blooming. 

THE  BLISTER  BEETLES.  Epicauta  sps. 
Blister  beetles  feed  on  sweet  pea  plants 
from  the  beginning  of  the  seedling  stage 
up  to  maturity.  Two  species  of  blister 
beetles  are  troublesome  to  sweet  peas ;  the 
black  and  the  striped. 


INSECT  PESTS  169 

THE  BLACK  BLISTER  BEETLE.  Epicauta 
pennsylvanica  DeG.  As  the  name  implies, 
this  bettle  is  uniformly  black.  It  meas- 
ures a  little  over  a  quarter  of  an  inch  in 
length.  It  feeds  on  a  wide  range  of  plants 
such  as  the  potato,  tomato,  cabbage,  carrot, 
beet,  com,  bean,  aster,  clematis,  zinia, 
sweet  pea,  and  a  number  of  other  ornamen- 
tals. In  the  absence  of  other  food  it  is 
commonly  found  feeding  on  different  rag- 
weeds (Ambrosia  sp.),  on  golden  rod,  on 
amaranth,  and  on  iron  weed.  This  beetle, 
too,  has  a  wide  range  of  territory. 

THE  STRIPED  BLISTER  BEETLE.  Epi- 
cauta vittata  Fab.  This  species  is  about 
half  an  inch  in  length  with  blackish  wing 
covers,  each  of  which  is  bordered  with  yel- 
low and  has  a  yellow  stripe  down  the  cen- 
ter (fig.  38).  It  injures  potatoes,  toma- 
toes, beets  and  mangels,  turnips,  beans, 
peas,  radishes,  melons,  corn,  clover,  alfalfa, 


iyo     DISEASES  OF  THE  SWEET  PEA 


FIG.   38.      THE   STRIPED   BLISTER   BEETLE.       (AFTER   CHITTEN- 
DEN.) 

and  sweet  peas.  According  to  Professor 
Chittenden  1  the  beetle  lays  its  eggs  on 
plants  or  on  the  ground.  From  each  egg 
hatches  a  small  long-legged  larva,  which 
runs  actively  in  search  of  a  grasshopper 
egg  pod  which  it  enters  and  feeds  upon. 
Afterwards  it  casts  its  skin  several  times 
and  finally  becomes  transformed  into  a 
beetle. 

There  are  also  a  number  of  caterpillars 
which  feed  on  the  sweet  pea,  but  they  have 
as  yet  not  been  studied  carefully. 

1  United  States  Department  of  Agriculture,  Year 
Book,  1898. 


INSECT  PESTS 


171 


SOIL    INFESTING    INSECTS 

VARIEGATED  CUTWORMS.  Peridroma 
saucia.  These  are  common  garden  pests 
attacking  a  number  of  other  plants  as 
well  in  addition  to  the  sweet  pea  (fig. 
39  a  to  /) .  Cutworms  are  troublesome 
the  first  year  when  sweet  peas  are  planted 


FIG.  39.  VARIEGATED  CUT  WORM,  Q  MOTH.  &  LARVA 
FEEDING.  C  LARVA  RESTING.  d  EGGS  LAID  ON  DEAD 
TWIGS.  e  CLUSTER  OF  EGGS  MAGNIFIED.  (AFTER  CHIT- 
TENDEN.) 


172     DISEASES  OF  THE  SWEET  PEA 

on  old  sod.  They  are  sometimes  intro- 
duced into  a  new  place  with  the  compost. 
The  larvae  of  cut  worms  have  the  habit 
of  cutting  herbaceous  plants  at  the  stem 
end.  The  injury  is  inflicted  at  night  or 
on  dark  days:  the  worms  return  to  the 
ground  as  soon  as  the  sun  appears.  The 
adult  of  the  cutworm  is  a  moth  which 
lays  her  eggs  in  old  fields  or  pastures  where 
there  is  plenty  of  grass  for  the  young  larvae 
to  feed  upon.  As  the  young  hatch,  they 
feed  on  roots  of  grass.  The  first  season 
the  young  cutworms  usually  attain  about 
half  an  inch  in  length.  As  winter  ap- 
proaches they  build  earthen  cells  in  the 
ground  and  thus  protect  themselves  from 
cold  weather.  In  the  spring,  if  the  field 
is  allowed  to  remain  in  grass,  plenty  of 
food  is  on  hand  for  them.  However  when 
the  sod  is  plowed  under,  and  other  garden 
crops  planted,  such  as  the  sweet  pea,  the 


INSECT  PESTS  173 

natural  food  supply  of  the  worms  is  cut 
off  and  they  are  compelled  to  feed  on  the 
cultivated  plants.  These  are  severely  in- 
jured if  the  insects  are  abundant. 

WIREWORMS  Melanotus  communis  are 
a  prominent  pest  of  field  crops.  They 
are  the  young  of  click  beetles,  also  known 
as  snapping  bugs.  Wire  worms  are  brown 
hard  bodied  larvae  of  nearly  uniform  size 
throughout.  They  bore  into  various  seeds 
after  planting  or  work  on  the  roots  of 
various  plants,  often  causing  serious  in- 
jury. The  eggs  are  laid  on  old  pasture 
land,  and  the  larvae  which  hatch  from  them 
normally  work  on  the  roots  of  grasses.  If 
the  sod  is  replaced  by  any  other  cultivated 
crop,  the  larvae  are  forced  to  feed  on  that 
crop  for  want  of  its  normal  host  plant. 
Sweet  peas  often  suffer  from  this  pest, 
although  the  injury  is  not  apparent  until 
they  are  in  bloom. 


174    DISEASES  OF  THE  SWEET  PEA 

Differing  from  cut  worms,  wireworms 
pass  from  three  to  five  years  in  the  larvae 
stage;  hence  wireworms  of  different  ages 
may  be  found  in  the  same  place  feeding 
side  by  side. 

WHITE  GRUBS.  Lachnosterna  sp. 
White  grubs  are  the  larvae  of  May  beetles 
(fig.  40  a  to  /) .  They  are  injurious  to  a 


FIG.  40.  WHITE  GRUB  OR  MAY  BEETLE,  O  BEETLE,  b 
PUPA.  C  FULL  GROWN  LARVA  OR  WHITE  GRUB.  (AFTER 
CHITTENDEN.) 

number  of  cultivated  plants,  the  sweet  pea 
being  included.  May  beetles  lay  their 
eggs  in  sod,  in  corn  fields,  or  in  the  garden. 
The  grubs  hatch  about  the  middle  of  July 
and  begin  feeding  on  roots,  growing 


INSECT  PESTS  175 

slowly,  and  requiring  two  years  or  more 
to  become  full  size.  Larvae  of  proper  age 
and  size  change  to  pupse  in  midsummer 
and  the  adult  stage  is  reached  by  Septem- 
ber, but  the  beetles  remain  in  the  earthen 
cells  made  by  the  larvse  until  the  following 
spring.  Thus  it  is  seen  that  the  life  cycle 
of  white  grubs  is  similar  to  that  of  wire- 
worms.  Larvse  of  different  ages  are  pres- 
ent in  the  soil  at  all  times  in  the  year; 
hence  injury  caused  by  them  may  be  con- 
tinuous. 


CHAPTER  VIII 

DISEASED   SEEDS 

ANTHRACNOSE.  Under  the  discussion 
of  anthracnose  we  have  already  seen  that 
disease  may  be  transmitted  with  the  seed. 
In  that  case  infection  starts  on  the  pods 
and  the  disease  works  inwards,  gradually 
penetrating  the  seed  coat  and  the  seed 
proper  (fig.  41).  Such  seeds  when  har- 
vested have  a  shriveled  appearance  and 
when  planted  with  healthy  seeds  introduce 
the  trouble  into  the  soil. 

STREAK.  Another  disease  that  may  be 
transmitted  with  the  seeds  is  the  "streak." 
In  examining  infected  plants  we  can  read- 
ily see  that  the  disease  has  invaded  the 

pods  and  the  seeds  within.    When  such 
176 


Fig.  41. — Anthracnose  Disease  of  pods  and  seeds. 
The  arrows  shew  the  diseased  spots. 


DISEASED  SEEDS  177 

seeds  are  planted,  they  may  introduce  the 
parasite  into  the  soil. 

SHRIVELED  SEEDS.  Sweet  pea  seeds,  as 
sold  by  seedsmen,  as  put  up  in  small  paper 
packages.  In  very  few  cases  are  all  the 
seeds  plump  and  full.  A  certain  per  cent 
are  shriveled  and  give  the  appearance  of  be- 
ing diseased.  Such  seeds  are  not  always 
diseased.  These  shriveled  seeds  often  ger- 
minate as  readily  as  the  plump  ones,  and  as 
they  swell  cannot  be  told  from  others.  It 
seems  that  the  shriveling  is  correlated  with 
loss  of  water,  and  this  seems  to  be  charac- 
teristic of  some  varieties  more  than  of 
others.  However,  it  is  difficult  to  tell 
whether  such  seeds  in  the  long  run  produce 
weaker  plants  which  are  more  susceptible 
to  disease.  A  small  percentage  of  the 
shriveled  seeds  fail  to  germinate.  Some 
of  these  no  doubt  are  hard  seeds  which  can- 
not germinate  because  of  their  impervious 


178     DISEASES  OF  THE  SWEET  PEA 

seed  coats.  Others  upon  culturing  in  the 
laboratory  are  found  to  contain  a  variety 
of  fungi,  such  as  Alternaria,  Fusarium, 
Clonostachys,  Rhizopus,  and  Botrytis  (fig. 
42) .  These  seem  to  play  the  role  of  sap- 
rophytes on  the  growing  plants,  but  they 
may  be  weak  parasites,  capable  of  attack- 
ing these  few  shriveled  seeds  which  may 
lack  in  vigor  and  resistance. 

THE  DRUG  STORE  BEETLE.1  Sitodrepa 
panicea.  This  minute  beetle  (fig.  44) 
is  of  considerable  economic  importance 
to  seedsmen,  since  sweet  pea  seeds  in  the 
storehouse  are  very  frequently  seriously 
injured  by  it.  This  pest  is  often  found 
feeding  on  dry  bread,  and  because  of 
this,  it  is  known  in  Europe  as  the  bread 
beetle.  In  this  country  it  is  found  to 

^ee  also  Bull.  4.  Bur.  Entom.  U.  S.  Dept.  Agr., 
1896. 


Fig.  42. — To  the  left,  Fusarium  and  Botrytis  fungi  from 
shriveled  and  non-germinated  Sweet  Pea  seeds; 
to  the  right,  shriveled  seed  soaked  3  minutes  in  a 
2%  formaldehyde  solution. 


DISEASED  SEEDS  179 

be  a  very  common  pest  in  drug  stores, 
whence  its  name.  It  also  invades  mills, 
granaries,  and  warehouses  of  all  kinds. 
It  also  invades  the  kitchen  where  it  feeds 
on  red  pepper,  flour,  and  all  sorts  of 
breakfast  foods.  It  also  eats  ginger, 
rhubarb,  chocolate,  dried  fruits,  beans, 
peas,  coffee,  rice,  and  other  seeds  of  every 
description.  Its  larva  is  often  found  as  a 
book  worm.  The  larva  of  this  beetle  is 
so  voracious  that  it  is  said  to  "eat  anything 
except  cast  iron."  It  is  also  the  larva  of 
this  beetle  that  is  so  fond  of  sweet  pea 
seeds,  tunneling  the  inside,  and  thus  com- 
pletely destroying  the  germinating  power 
of  the  seed.  The  adult  beetles  mate  and 
the  female  lays  her  eggs  on  sweet  pea  seeds 
and  elsewhere.  The  young  upon  hatching 
at  once  begin  to  tunnel  into  the  seeds.  In 
the  storehouse  there  are  usually  four  broods 


i8o    DISEASES  OF  THE  SWEET  PEA 

formed  during  the  winter  and  if  allowed 
free  range  may  destroy  large  quantities  of 
seed. 

Seedsmen  whose  storehouses  are  serious- 
ly infested  with  these  pests  will  find  relief 
by  the  use  of  bisulphide  of  carbon  evapo- 
rated at  the  rate  of  one  pound  of  the  chem- 
ical to  each  1,000  feet  of  cubic  space. 
While  fumigating,  the  room  should  be 
closed  tightly  and  care  taken  to  keep  away 
lighted  cigars,  matches,  or  burning  candles. 


Fig.  43.— Auto  Spray 
No.  i. 

Courtesy  of  E.  C.  Brown  Co., 
Rochester,  N.  Y. 


Fig.  44. — The  Drug-store  Beetle,  an  enemy  to  stored 
Sweet  Pea  seeds. 


CHAPTER  IX 

PHYSIOLOGICAL   DISEASES 

PHYSIOLOGICAL  diseases  are  those  dis- 
turbances of  the  normal  activity  of  a  plant 
which  are  not  induced  by  fungi,  bacteria, 
or  insects. 

BUD  DROP.  The  young  flower  buds  at  a 
very  early  age,  turns  yellow  and  drops  off. 
This  disease  is  sometimes  confused  with 
the  drop  produced  by  the  anthracnose  dis- 
ease. In  the  latter  case  the  flower  develops 
into  a  normal  spike,  but  it  is  attacked  soon 
by  the  fungus,  Glomerella  rufomaculans, 
which  girdles  it  at  the  point  of  attachment 
between  the  flower  and  the  peduncle.  In 
this  case  the  blossom  falls  off,  leaving  be- 
hind the  beheaded  peduncle.  In  bud  drop, 

181 


182     DISEASES  OF  THE  SWEET  PEA 

however,  the  minute  young  blossoms  fail 
to  develop,  and  drop  off  while  very  young. 

This  form  of  drop  is  attributed  to  an 
unbalanced  condition  of  food  elements  in 
the  soil.  This  may  occur  in  a  soil  that  has 
been  excessively  fed  or  in  a  soil  that  is 
lacking  in  plant  food.  Bud  drop  has  ac- 
tually been  found  in  the  laboratory  on 
sweet  pea  plants  grown  in  pots  which  re- 
ceived heavy  applications  of  manure,  and 
in  pots  filled  with  a  very  poor  clay  soil. 
The  trouble  has  been  overcome  by  the  ap- 
plication of  150  Ib.  of  muriate  of  potash 
and  600  Ib.  of  acid  phosphate  per  acre. 
As  a  result  of  this  treatment  the  drop 
ceased  within  a  week,  and  a  luxuriant  crop 
of  flowers  was  produced.  An  application 
of  a  balanced  fertilizer  to  the  pots  above 
mentioned  readily  helped  the  plants  to 
overcome  the  drop. 

ROOT  BURN.    This  trouble,  probably,  is 


PHYSIOLOGICAL  DISEASES       183 

a  physiological  disease.  It  is  induced  by 
the  excessive  use  of  fertilizers.  The  fol- 
lowing facts  from  the  letter  of  a  grower 
who  wrestled  with  this  trouble  will  help  to 
confirm  the  belief  in  the  physiological 
nature  of  this  disease:  "The  seeds  were 
sown  November  i  in  pots  and  planted  De- 
cember 15  in  the  beds  in  the  greenhouse. 
Previous  to  the  planting,  the  beds  were 
well  manured  with  horse  manure,  which 
was  applied  six  months  before  planting. 
Besides  this,  wood  ashes  were  also  applied 
at  the  rate  of  1,500  Ib.  to  4,500  square  feet 
of  bed  space.  This  would  be  equivalent 
to  nearly  seven  and  one-half  tons  per  acre. 
About  one  month  after  planting,  some  of 
the  plants  turned  yellow  and  died ;  others 
remained  dwarfed  and  offered  a  languid 
appearance."  Upon  examining  some  of 
the  plants,  they  were  found  to  be  dwarfed 
and  to  have  a  sickly  yellowish  look.  The 


184    DISEASES  OF  THE  SWEET  PEA 

roots  were  dwarfed,  blackened  as  though 
burned,  resembling  the  injury  of  Thielavia 
root  rot.  Upon  testing  the  soil  it  was 
found  to  be  strongly  alkaline.  Hard  wood 
ashes,  contain  about  30  per  cent  caustic 
lime  and  from  5  to  12  per  cent  potash.  It 
was  the  excess  of  both  of  these  substances 
that  made  the  soil  so  alkaline,  the  roots  of 
the  sweet  peas  becoming  burned  and  inhib- 
iting growth.  This  kind  of  injury  could 
be  considered  purely  physical ;  nevertheless 
any  injury  which  interferes  with  the  nor- 
mal functions  of  the  parts  of  the  plants 
also  results  in  a  disturbance  in  its  metabol- 
ism, and  is  therefore  considered  as  a  physio- 
logical trouble.  A  remedy  for  this  was 
found  in  the  use  of  acid  phosphate,  fol- 
lowed by  a  good  drenching  of  water.  This 
helped  to  neutralize  the  alkalinity  and  to 
balance  the  food  rations  in  the  soil. 


CHAPTER  X 

METHODS    OF    CONTROL 

GROWERS  who  expect  to  find  in  these 
pages  a  "cure  all"  for  their  sweet  pea  trou- 
bles will  be  disappointed.  Once  a  tender 
sweet  pea  plant  is  invaded  by  fungi  or  bac- 
teria it  can  rarely  be  cured.  Insects,  how- 
ever, may  be  destroyed,  since  it  is  possible 
to  poison  them,  although  the  task  is  often 
difficult  because  they  are  not  easily  ac- 
cessible. 

The  problem,  therefore,  is  one  of  pre- 
vention. Sweet  pea  growers  would  win 
ninety  per  cent  of  the  battle  if  they  would 
realize  the  importance  of  preventive  meth- 
ods. Here,  as  elsewhere,  the  old  dictum 
holds  true,  "an  ounce  of  prevention  is 
185 


i86     DISEASES  OF  THE  SWEET  PEA 

worth  a  pound  of  cure."  Yet  even  here, 
the  personal  element  is  the  determining 
factor  in  success.  Growers  too  often  work 
by  "rule  o'  thumb."  Some  have  their  pet 
theories  as  to  causes  of  disease ;  others  have 
their  remedies,  favorite  fungicides  in- 
tended to  act  as  a  cure  all  but  which  do  not 
often  yield  the  promised  results.  Progres- 
sive growers  find  it  profitable  to  keep  in 
close  touch  with  Plant  Pathologists  in  the 
various  Experiment  Stations.  More  than 
this,  every  grower  should  develop  the 
power  of  keen  observation,  for  plant  dis- 
eases are  too  often  not  detected  until  too 
late. 

RESISTANT   VARIETIES 

The  most  promising  means  of  control  is 
the  use  of  resistant  varieties.  It  is  true 
that  resistant  varieties  will  encourage  the 
lazy  man  to  neglect  his  seed,  disregard  ro- 
tation, and  overlook  all  sanitary  methods; 


METHODS  OF  CONTROL         187 

nevertheless,  resistant  varieties  are  often 
the  only  protection  against  complete  an- 
nihilation of  a  species  by  disease.  In  pass- 
ing through  a  sick  field,  one  cannot  help 
but  notice  that  not  all  the  plants  of  the 
same  kind  are  subject  alike  in  the  same 
way  to  the  disease.  Some  are  killed  out- 
right;  others  are  partly  affected,  or  if  badly 
affected,  resist  the  disease ;  and  still  others 
are  not  at  all  diseased.  If,  therefore,  we 
are  able  to  select  the  seed  from  the  resistant 
strain  and  multiply  it  rapidly,  we  will  ob- 
tain resistant  plants  capable  of  producing 
100  per  cent  healthy  plants  in  a  sick  soil. 
That  this  is  possible  there  can  be  no  doubt. 
A  strain  of  cowpeas  has  been  obtained 
which  is  resistant  to  wilt,  and  a  strain  of 
clover  has  also  been  obtained  which  is  re- 
sistant to  anthracnose.  Of  course,  it  can- 
not be  expected  that  a  strain  will  be  re- 
sistant to  every  disease,  but  there  is  no 


i88    DISEASES  OF  THE  SWEET  PEA 

doubt  that  we  may  obtain  strains  resistant 
to  more  than  one  disease. 

SEED   TREATMENT 

It  was  previously  shown  that  the  seeds 
are  capable  of  carrying  anthracnose  and 
possibly  also  the  streak  disease.  It  is 
therefore  unwise  to  plant  sweet  pea  seeds 
without  first  treating  them.  Heating  the 
seed  in  hot  water  at  various  temperatures 
of  100  degrees,  90,  80,  70  and  60  de- 
grees C.  from  one  second  to  five  minutes 
does  not  seem  to  yield  promising  results. 
Soaking  the  seed  in  sulphuric  acid  from 
five  to  fifteen  minutes  helps  to  accelerate 
germination,  especially  of  the  hard  seed; 
and  it  also  destroys  all  harmful  germs 
which  adhere  to  the  seed  coat.  After  soak- 
ing the  seeds  in  the  sulphuric  acid,  they 
should  be  thoroughly  washed  in  running 
water,  then  dried  and  planted  in  the  usual 


METHODS  OF  CONTROL         189 

way.  Treating  the  seed  with  the  acid  for 
one  hour  will  greatly  reduce  its  percentage 
of  germination,  and  by  prolonging  the 
treatment  to  one  and  a  half  hours,  germina- 
tion will  be  inhibited  altogether. 

Soaking  the  seed  in  a  solution  of  one 
pint  of  formaldehyde  in  30  gallons  of 
water  for  ten  minutes  will  also  destroy 
spores  which  adhere  to  the  seed  coat.  The 
formaldehyde  treatment  however  does  not 
seem  to  help  the  germination  of  the  seed. 
It  should  not  be  expected  that  the  seed 
treatment  will  remove  all  evils.  It  is  only 
beneficial  in  that  it  kills  all  spores  of 
parasitic  fungi  which  may  adhere  to  the 
seed  coat.  Seeds  which  are  diseased  and 
which  have  their  interior  tissue  invaded  by 
parasitic  organisms  will  not  be  benefited 
by  the  treatment,  since  the  chemical  cannot 
penetrate  the  seed  to  reach  the  interior 
lodging  parasite.  The  use  and  selection 


igo    DISEASES  OF  THE  SWEET  PEA 

of  clean,  healthy,  plump  seeds  is  as  im- 
portant as  the  seed  treatment. 

CONTROL   OF   SICK   SOILS 

The  habit  of  many  growers  of  sweet 
peas  is  to  use  the  same  soil  in  the  beds  for 
a  period  of  years.  It  is  even  claimed  that 
this  practice  tends  to  produce  stronger 
vines.  This  may  be  true  as  long  as  the  soil 
remains  uninfected.  However,  no  sooner 
does  contamination  set  in  with  either  Rhi- 
zoctonia,  Fusarium,  Thielavia,  Chaetom- 
ium,  or  the  eel  worm,  than  it  becomes  diffi- 
cult, if  not  impossible,  to  obtain  a  stand  of 
sweet  peas.  The  remedy  of  course  is  to 
throw  out  the  old  soil  and  bring  in  fresh 
dirt  free  from  disease.  This  unfortunate- 
ly is  not  always  a  safe  method,  for  the  rea- 
son that  the  new  soil  too  may  be  contami- 
nated, or  that  it  may  readily  become  in- 
fected as  soon  as  it  is  placed  in  the 


Fig-  45- — Soil  infected  with  Fusarium  lathyri,  the  cause 
of  Sweet  Pea  Wilt:  a.  the  soil  was  steam-sterilized, 
resulting  in  a  perfect  stand;  b.  check  unsterilized. 
The  seedlings  in  both  pots  are  of  the  same  age. 


METHODS  OF  CONTROL          191 

previously  contaminated  bed.  Infected 
greenhouse  soil  may  be  rendered  useful 
and  free  from  disease  by  either  the  steam 
or  the  formaldehyde  methods  of  steriliza- 
tion. 

(a)  STEAM  STERILIZATION.  This  method 
is  practical  in  the  greenhouse  (fig.  45) 
or  on  seed  beds  only  where  the  areas  are 
limited.  Its  use  is  possible  only  where 
steam  is  to  be  had  from  a  boiler  capable 
of  producing  from  80  to  90  Ib.  pressure. 
The  method  of  sterilization  is  as  follows  : 
before  planting,  prepare  the  soil  in  the 
regular  way,  adding  the  necessary  amount 
of  manure  and  fertilizers.  At  the  bottom 
of  the  bed  or  bench,  pipes  or  drain  tiles  are 
laid  parallel  to  each  other  two  feet  apart. 
The  pipes  are  perforated  with  i -6-inch 
holes  throughout.  These  pipes  or  tiles  are 
closed  at  the  farthest  end  so  that  the  steam 
may  come  out  through  the  cracks  or  holes. 


192     DISEASES  OF  THE  SWEET  PEA 

The  other  end  of  the  tiles  or  pipes  fits  into 
a  cross-pipe  which  is  connected  with  the 
main  steam  pipe  in  the  boiler.  The  steam 
is  now  turned  on  and  as  fast  as  it  escapes 
from  the  holes  it  penetrates  and  heats  the 
soil  in  the  bench  or  bed.  The  steam  is 
turned  on  from  one  to  two  hours  according 
to  the  constancy  and  strength  of  the  pres- 
sure. A  good  method  of  determining  when 
to  turn  off  the  steam  is  to  bury  a  few  raw 
potatoes  at  the  surface  of  the  bed  and  cover 
them  with  some  straw  or  sacking.  When 
the  potatoes  are  cooked  the  sterilization 
has  been  completed.  This  method  of  ster- 
ilization has  the  advantage  of  killing  the 
eel  worm  and  all  the  other  soil  troubles  as 
well  as  the  weeds.  As  above  described,  it 
is  somewhat  expensive  in  the  initial  cost  of 
installation.  But  once  put  in,  it  serves  a 
number  of  years,  and  the  pipings  too  may 


METHODS  OF  CONTROL          193 

be  used  for  sub-irrigation,  a  very  desirable 
method  of  watering  the  beds. 

A  cheaper  method  of  steam  sterilization 
is  the  "inverted  pan  method,"  which  may 
also  be  used  to  sterilize  seed  beds  and 
frames  outdoors.  The  method  has  given 
excellent  results  and  because  of  its  sim- 
plicity and  small  cost  is  recommended 
for  use  in  large  or  small  areas.  It  is  the 
invention  of  Mr.  A.  D.  Shamel  of  the 
United  States  Department  of  Agricul- 
ture. The  apparatus  consists  »f  a  gal- 
vanized iron  pan  6  ft.  by  10  ft.  and  6  in. 
deep,  which  is  inverted  over  the  soil  to 
be  sterilized,  and  steam  is  admitted  under 
pressure.  The  pan  is  supplied  with  steam 
hose  connections,  has  sharp  edges  which 
are  forced  into  the  soil  on  all  sides  to  pre- 
vent the  escape  of  steam,  and  is  fitted  with 
handles  for  moving  it  from  place  to  place, 


194    DISEASES  OF  THE  SWEET  PEA 

the  weight  of  the  entire  pan  not  being  over 
400  Ib.  The  soil  to  be  sterilized  is  pre- 
pared as  in  the  previous  method,  a  few 
potatoes  being  buried  to  gauge  the  amount 
of  heat  produced.  The  steam  is  kept  at 
as  high  a  pressure  as  possible,  80  to  100 
Ib.  being  best,  for  one  to  two  hours  accord- 
ing to  the  pressure  maintained.  When 
one  section  of  the  bed  is  treated,  the  pan 
is  lifted  and  carried  to  an  unsterilized  por- 
tion and  the  operation  is  repeated  until  the 
entire  bed  is  steamed. 

(b)  FORMALDEHYDE.  When  steam  ster- 
ilization is  not  feasible  because  of  the 
absence  of  a  steam  boiler  or  for  some  other 
reason,  the  formaldehyde  treatment  is  the 
next  best.  It  will  kill  Thielavia,  Fusar- 
ium,  Rhizoctonia,  Pithyium,  and  Chaeto- 
mium  in  infected  soils.  It  is  doubtful, 
however,  if  it  will  entirely  remove  eel 
worms  from  such  soils.  The  formal de- 


METHODS  OF  CONTROL          195 

hyde  method  is  applied  as  follows: 
The  beds  are  thoroughly  prepared  in  the 
same  way  as  in  other  methods  of  steriliza- 
tion and  are  drenched  with  a  formalin  solu- 
tion composed  of  one  pint  of  commercial 
formaldehyde  to  25  gallons  of  water,  one 
gallon  of  this  solution  being  used  to  each 
square  foot  of  bed  space.  The  solution 
should  be  put  on  with  a  watering  can  and 
distributed  as  evenly  as  possible  over  the 
bed  so  as  to  wet  the  soil  thoroughly  to  the 
depth  of  a  foot.  It  will  in  most  cases  be 
necessary  to  apply  this  solution  two  or 
three  times,  as  the  soil  will  not  absorb  this 
quantity  of  liquid  at  one  time.  After  the 
treatment  the  beds  should  be  covered  with 
heavy  burlap  to  keep  in  the  fumes  for  a 
day  or  so,  and  then  aired  for  a  week  before 
planting.  Stirring  the  soil  at  this  time 
helps  the  escape  of  the  formaldehyde 
fumes. 


196     DISEASES  OF  THE  SWEET  PEA 

(c)  INFECTED  AREAS.    In   the   green- 
house, damping  off  or  any  other  of  the  soil 
troubles  usually  starts  at  one  part  in  the 
bed  and  from  there  spreads  all  over  the 
bed.    Where  only  a  few  of  these  centers  of 
infection  occur,  much  damage  may  be  pre- 
vented by  immediately  removing  the  in- 
fected plants  and  soil  from  the  bed  to- 
gether with  the  surrounding  area  somewhat 
beyond  the  last  signs  of  disease. 

(d)  CULTURAL  CONSIDERATIONS.  Every 
factor  which  leads  to  a  weakening  of  the 
plants  should  be  eliminated.     In  the  green- 
house, overfeeding  as  well  as  underfeed- 
ing, overwatering,  and  excessive  high  tem- 
peratures with  lack  of  ventilation  should 
be  avoided. 

(e)  OTHER  PREVENTIVE  METHODS  IN 
THE  GREENHOUSE.    Usually  the  soil  in 
the  greenhouse  is  infected  with  manure, 
with  potted  plants  started  early  in  a  cold 


METHODS  OF  CONTROL          197 

frame,  or  with  diseased  tomatoes,  the 
violets,  and  a  number  of  other  hosts  grown 
as  alternating  crops.  It  goes  without  say- 
ing that  the  grower  should  not  knowingly 
bring  in  sick  soil  into  the  greenhouse,  nor 
should  a  sick  soil  from  indoors  be  dumped 
in  the  open  where  sweet  peas  or  any  other 
crops  are  likely  to  be  grown  for  ornamental 
or  commercial  use.  Care  should  be  taken 
to  allow  no  access  to  diseased  violets  or 
diseased  plants  of  any  kind. 

CONTROL   OF  OUTDOOR   SICK  SOILS 

Unlike  greenhouse  soils,  affected  areas 
outdoors  are  not  so  easily  treated.  In  a 
small  garden  plot,  as  in  the  home  garden 
for  instance,  a  sick  soil  may  be  sterilized 
either  with  steam,  using  the  inverted  pan 
method,  or  with  formaldehyde,  as  in  the 
case  of  the  greenhouse.  Where  sweet  peas 
are  grown  on  a  large  scale,  as  for  seed  pur- 


198    DISEASES  OF  THE  SWEET  PEA 

poses,  the  problem  of  handling  sick  soils 
becomes  a  more  difficult  matter.  In  this 
case  neither  the  formaldehyde  nor  the 
steam  methods  are  applicable,  since  either 
is  too  expensive  when  used  on  a  large  scale 
and  hence  is  not  practical.  There  are, 
however,  other  control  measures  which  may 
prove  helpful. 

(a)  CLEANLINESS.  It  is  a  common  prac- 
tice to  allow  sweet  pea  plants  which  have 
passed  their  usefulness  to  winter  over  in 
the  field.  As  spring  comes,  the  dead  vines 
are  plowed  under.  In  cases  of  fall  plow- 
ing and  sowing  the  old  vines  are  immedi- 
ately turned  under.  Should  these  vines 
have  suffered  from  disease  the  previous 
season,  they  would  at  once  re-infect  the  soil. 
As  time  goes  on  the  land  may  become  so 
contaminated  as  to  be  unfit  for  sweet  peas 
for  a  number  of  years.  To  obviate  this 
the  old  vines  should  be  burned  as  soon  as 


METHODS  OF  CONTROL          199 

they  pass  all  usefulness  and  as  soon  as  they 
have  sufficiently  dried.  The  expense  and 
the  labor  of  this  operation  should  not  in- 
fluence the  grower  to  neglect  this.  This  is 
especially  true  for  the  seedsman  whose 
success  depends  largely  on  clean  lands  in 
order  to  produce  clean  seed  which  will 
meet  the  market  requirements. 

(b)  MANURE.  Florists  and  growers 
often  dump  potted  plants  on  the  manure 
pile  or  on  the  compost.  Such  plants  may 
often  be  infected  with  some  of  the  soil 
troubles  to  which  the  sweet  pea  is  sus- 
ceptible. The  use  of  such  infected  manure 
or  compost  may  mean  the  ruin  of  an  entire 
field.  To  avoid  outdoor  contamination  of 
our  sweet  pea  soils,  extreme  care  must  be 
taken  that  no  contaminated  manure  or 
compost  find  its  way  into  the  plantations, 
(c)  CROP  ROTATION.  This  is  an  essen- 
tial and  effective  means  of  controlling  soil 


200     DISEASES  OF  THE  SWEET  PEA 

sickness.  With  this  system  the  parasite  is 
starved  out  for  lack  of  the  proper  hosts. 
With  the  sweet  pea,  the  selection  of  hosts 
for  proper  rotation  is  a  difficult  one.  So 
many  of  the  cultivated  and  ornamental 
plants,  for  instance,  are  subject  to  the  root 
rots  which  also  attack  sweet  peas.  The 
safest  method,  perhaps,  for  seed  grow- 
ers, would  be  to  have  sweet  peas  alternated 
every  second  or  third  year  with  a  cereal 
such  as  sweet  corn,  sugar  cane,  or  millet. 
Where  soils  are  already  badly  affected, 
sweet  peas  should  be  grown  on  the  same 
land  every  fifth  or  sixth  year. 

(d)  FERTILIZERS.  Outdoor  sweet  peas 
are  not  as  yet  known  to  suffer  from  eel 
worm  attacks.  However,  should  this  oc- 
cur, increase  of  fertilizer  will  undoubtedly 
prove  to  be  a  good  method  of  handling 
root  knot  by  forcing  the  growth  of  the  root 


METHODS  OF  CONTROL         201 

system.  Observations  show  that  nema- 
tode  injury  is  confined  to  the  upper  roots 
of  the  plant,  that  is,  those  which  are  12  to 
16  inches  deep.  Hence,  if  the  roots  are 
induced  to  penetrate  deeper  in  the  soil, 
part  of  the  injurious  effect  will  be  over- 
come. Potassium  salts  have  been  found 
to  be  beneficial,  especially  in  soils  poor  in 
potash.  It  has  been  found  in  Germany 
that  the  sugar  beet  nematode  removes 
equally  all  mineral  salts  from  the  roots. 
Therefore  to  improve  such  a  condition  we 
would  need  to  add  only  that  mineral  which 
was  originally  lacking.  This  may  explain 
the  effect  of  potash  in  combating  this  dis- 
ease. 

CONTROL  OF  SOIL-INFESTING  INSECTS. 
Spraying  the  soil  will  be  of  little  value  in 
the  control  of  underground  insect  pests. 
Where  wire  worms  are  causing  injury  to 


202     DISEASES  OF  THE  SWEET  PEA 

the  roots  of  sweet  pea  plants,  sow  corn 
which  has  been  soaked  for  ten  days  in  water 
containing  arsenic  or  strychnine  before  the 
sweet  pea  seeds  are  planted.  The  larva 
will  attack  the  poisonous  corn  kernels  and 
die.  Another  way  is  to  scatter  poisoned 
and  sweetened  corn  meal  dough  which  will 
act  as  a  bait. 

White  grubf  may  be  controlled  by  the 
use  of  bisulphide  of  carbon  and  kerosene 
emulsion.  The  latter  is  diluted  about  ten 
times  and  poured  on  the  ground  about  the 
infected  plants.  This,  however,  is  a  risky 
procedure.  Fall  plowing  is  a  valuable 
remedy  since  many  of  the  grubs  are  thus 
exposed  to  the  cold  winter  weather  and 
killed. 

Cut  worms  may  be  controlled  by  the  use 
of  a  poisoned  bran  made  as  follows:  to 
three  ounces  of  molasses  add  one  gallon 
of  water,  and  sufficient  bran  to  make  a 


METHODS  OF  CONTROL         203 

fairly  stiff  mixture.  To  this  add  Paris 
green  or  arsenic  and  stir  well  into  a  paste. 
A  heaping  teaspoonful  of  the  mixture  is 
scattered  here  and  there  over  the  infested 
land. 


CHAPTER  XI 

SPRAYING 

GENERAL  CONSIDERATIONS.  The  or- 
chardist,  the  nurseryman,  the  gardener, 
and  the  florists  have  already  learned  the 
necessity  of  spraying.  It  often  determines 
whether  they  shall  lose  a  large  part  of  the 
crop  or  get  from  it  the  largest  possible 
profit  obtainable.  It  is  doubtful  if  sweet 
pea  growers  have  come  to  this  important 
realization.  Many  writers  on  sweet  peas 
have  in  the  past  attempted  to  give  the  im- 
pression that  this  species  is  usually  free 
from  insect  and  fungous  pests.  This  has 
unfortunately  led  to  an  indifference  that 
resulted  in  the  quick  dissemination  of  a 
number  of  dangerous  diseases.  The  streak 
204 


SPRAYING  205 

which  is  causing  so  much  loss  to  sweet  peas 
in  England  has  gained  a  strong  foothold  in 
this  country,  yet  prominent  growers  and 
seedsmen  strenuously  deny  the  existence 
of  this  disease  here.  The  anthracnose  is 
another  serious  disease,  and  yet  few  grow- 
ers have  a  first  hand  knowledge  of  its  ex- 
istence. The  time  is  rapidly  coming  when 
the  sweet  pea  like  every  other  important 
crop  will  have  to  be  sprayed.  The  grower 
who  fails  to  do  so  will  be  crowded  out  be- 
cause of  competition  with  others  more 
careful.  It  is  true  that  spraying  is  no 
pleasant  pastime  for  the  grower ;  neverthe- 
less, it  is  a  necessary  evil,  if  evil  it  may  be 
called. 

Spraying  has  two  aims :  to  kill  the  insect 
and  animal  pests,  and  to  control  fungous 
diseases.  The  substances  which  are  used 
for  the  one  are  without  effect  on  the  other. 

INSECTICIDES.    All   animal   and   insect 


206     DISEASES  OF  THE  SWEET  PEA 

pests  are  best  controlled  by  the  use  of  poi- 
sonous mixtures  applied  in  the  form  of 
liquid  sprays  or  powders.  Insecticides 
may  be  classified  as  internal  or  stomach 
poisons,  and  external  or  contact  poisons. 
The  former  kill  the  biting  insects  which 
take  it  into  the  stomach  with  the  food;  the 
latter  kill  by  direct  contact,  and  either 
causes  an  irritation  of  the  surface  of  the 
body  or  clogs  the  respiratory  openings  of 
sucking  pests. 

(a)  STOMACH  POISONS.  Paris  green  is 
one  of  the  best  known  of  stomach  poisons. 
When  chemically  pure,  it  is  composed  of 
copper  oxide,  acetic  acid,  and  arsenious 
acid.  It  destroys  cutworms,  caterpillars, 
beetles,  grubs,  slugs,  etc.  On  the  sweet 
pea  it  should  be  applied  preferably  as  a 
liquid,  using  one  pound  of  the  poison  and 
one  pound  of  lime  to  two  hundred  gallons 
of  water.  Paris  green  tends  to  sink  to  the 


SPRAYING  207 

bottom  of  this  mixture,  and  to  avoid  this 
it  must  be  constantly  stirred  while  being 
applied.  This  chemical  is  often  adulter- 
ated with  white  arsenic,  causing  it  to  badly 
scorch  the  treated  plants. 

For  sweet  peas,  the  use  of  arsenate  of 
lead  is  to  be  preferred  to  Paris  green,  since 
it  is  less  liable  to  scorch  the  foliage,  and 
adheres  better.  Its  chemical  composition 
consists  of  acetate  of  lead  and  arsenate- of 
soda.  It  is  applied  to  the  best  advantage 
as  a  liquid,  using  about  three  pounds  to 
100  gallons  of  water. 

Arsenite  of  zinc  may  also  be  used.  It  is 
a  very  finely  divided  fluffy  white  powder 
which  distributes  and  adheres  well  to  the 
foliage.  It  is  intermediate  between  Paris 
green  and  lead  arsenate  in  strength,  and 
costs  less  than  either. 

It  is  essential  when  arsenicals  are  used 
to  see  that  they  are  correctly  labeled,  and 


208    DISEASES  OF  THE  SWEET  PEA 

kept  under  lock  and  key  as  they  are  poison- 
ous to  man  and  animals. 

Hellebore  or  white  hellebore  is  some- 
what less  dangerous  than  the  arsenicals. 
However,  it  loses  its  insecticidal  value  by 
being  exposed  to  the  air.  It  is  a  specific 
against  slugs  in  the  greenhouse. 

(b)  CONTACT  POISONS.  All  the  tobacco 
or  nicotine  products  sold  principally  as  ex- 
tracts or  powders  belong  to  this  class.  A 
common  brand  much  used  is  the  prepara- 
tion known  as  "Black  leaf  40,"  diluted  1 
part  to  700  or  800  of  water.  An  addition 
of  soap  at  the  rate  of  two  bars  to  each  100 
gallons  of  the  solution  increases  its  effec- 
tiveness by  making  it  spread  out  better. 
Aphine,  Sulpho  tobacco,  and  a  number  of 
other  products  found  on  the  market  are 
usually  valuable  as  contact  poisons  if  prop- 
erly tested  out  and  guaranteed  by  the 
dealers. 


SPRAYING  209 

FUNGICIDES.  These  are  poisons  used  to 
control  fungous  pests.  As  previously 
stated,  some  parasitic  fungi  live  on  the  sur- 
face of  the  leaves  and  stems  and  are  there- 
fore easily  controlled.  An  example  of  this 
is  the  sweet  pea  mildew.  Other  fungi,  and 
these  are  by  far  in  the  majority,  are  those 
which  live  parasitically  in  the  tissue  of  the 
host,  and  therefore  cannot  be  reached. 
Fungicides  are  only  helpful  in  preventing 
entrance  of  the  parasite  in  the  host.  Fun- 
gicides are  ineffective  in  controlling  insect 
pests,  as  are  insecticides  in  controlling 
fungous  pests. 

(a)  BORDEAUX  MIXTURE.  This  is  the 
standard  fungicide,  especially  valuable  in 
controlling  the  sweet  pea  anthracnose. 
The  strength  used  should  be  3  Ib.  of  cop- 
per sulphate,  also  known  as  blue  stone,  4 
Ib.  lime,  and  50  gallons  of  water.  The 
easiest  way  to  prepare  it  is  to  dissolve  thor- 


210    DISEASES  OF  THE  SWEET  PEA 

oughly  the  blue  stone  in  25  gallons  of 
water.  Use  the  best  quality  of  lime  and 
slake  it  in  a  little  hot  water,  being  careful, 
however,  not  to  flood  it  while  slaking,  nor 
to  let  it  become  too  dry.  When  the  slak- 
ing is  completed,  add  enough  water  to 
make  25  gallons.  Mix  the  lime  water  and 
the  blue  stone  solutions,  using  first  one 
part  of  lime  water,  then  another  part  of 
the  blue  stone.  Strain  and  use  at  once. 
It  is  essential  that  the  lime  shall  not  be 
air  slaked  before  it  is  used. 

The  lime  water  and  the  blue  stone  solu- 
tions will  keep  a  long  time  if  they  are  kept 
in  separate  receptacles  and  well  covered. 
However,  after  they  are  once  combined,  it 
must  be  used  the  same  day.  Bordeaux 
mixture  more  than  a  day  old  is  useless. 
Where  Bordeaux  is  used  extensively,  stock 
solutions  of  lime  and  blue  stone  should  be 
prepared  and  ready  for  use. 


SPRAYING  211 

(b)  AMMONIACAL  COPPER  CARBONATE. 
The  objection  to  the  use  of  Bordeaux  is 
that  it  stains  the  leaves  and  foliage  of  the 
sweet  pea  plant.    This  is  not  a  serious  ob- 
jection when  sweet  peas  are  grown  for 
seeds  or  even  commercially  as  a  cut  flower. 
However,  when  grown  in  conservatories 
or  in  public  parks  for  ornamental  purposes, 
the  use  of  Bordeaux  becomes  objection- 
able.   In  this  case  ammoniacal  copper  car- 
bonate may  take  the  place  of  Bordeaux, 
since  the  former  is  a  colorless  material.    It 
is  prepared  as  follows : 

Copper  carbonate 5oz. 

Ammonia  (26°  Baume')   3  pints 

Water 50  gallons 

This  fungicide  should  be  used  as  soon  as 
it  is  made,  as  the  ammonia  evaporates 
quickly. 

(c)  POTASSIUM  SULPHIDE.    This  is  a 
valuable  fungicide  for  the  control  of  the 


212     DISEASES  OF  THE  SWEET  PEA 

sweet  pea  mildew.  The  following  strength 
is  recommended  : 

Potassium  sulphide 4oz. 

Water 10  gallons 

(d)  SULPHUR.  Flowers  of  sulphur  are 
often  used  in  greenhouses  to  control  the 
sweet  pea  mildew.  It  may  be  applied 
either  by  hand  or  with  a  duster. 

There  are  a  number  of  other  fungicides 
on  the  market  which  are  not  mentioned. 
They  should  be  thoroughly  tested  before 
they  are  used.  Considerable  discretion 
should  be  exercised  before  using  a  new 
fungicide  which  claims  to  be  a  "cure  all." 

COMBINATION  SPRAYS.  In  the  discus- 
sion of  the  foregoing  chapters  on  fungous 
and  insect  pests,  it  is  seen  that  the  sweet 
pea  is  subject  to  the  attacks  of  more  than 
one  disease.  Spraying,  if  properly  done, 
is  effective  in  controlling  or  in  keeping  in 


SPRAYING  213 

check  all  the  pests  which  attack  all  the 
parts  of  the  plant  above  ground.  The  va- 
rious spray  solutions  which  may  or  may  not 
be  combined  are  indicated  by  Cooley  and 
Swingle  *  in  the  following  table : 

Tobacco     Lime      Bordeaux 
extracts  sulphur      mixture 

Paris  green  yes  no          yes 

Arsenate  of  lead  yes  yes         yes 

Arsenite  of  zinc  (ortho)  yes  *            no 

Arsenite  of  lime  yes  no          yes 

Lime  sulphur  yes        

Bordeaux  yes        

*  The  advisability  of  making  these  two  combinations 
needs  further  investigation. 

Each  of  these  preparations  is  mixed  and 
applied  just  as  if  it  were  used  alone.  A 
combination  of  the  ammoniacal  copper 
carbonate  with  an  arsenate  would  be  un- 
safe, since  the  ammonia  renders  the  arsenic 

1  Cooley,  R.  A.,  and  Swingle,  D.  B.,  A  spraying  pro- 
gram for  Montana  orchards.  Montana  Agr.  Expt.  Sta- 
tion, Circ.  17:  119-151,  1912. 


214    DISEASES  OF  THE  SWEET  PEA 

more  soluble,  and  hence  may  result  in  the 
burning  of  the  sweet  pea  foliage.  How- 
ever, it  may  be  mixed  to  advantage  with 
the  tobacco  products. 

Careful  investigations  of  Professor 
Saf ro,  Entomologist  to  the  Kentucky  To- 
bacco Product  Co.,  show  that  "Black  leaf 
40"  may  be  used  in  combination  with  such 
spray  chemicals  as  lime  sulphur,  arsenate 
of  lead,  arsenite  of  zinc,  and  iron  sulphate 
for  controlling  sucking  and  chewing  in- 
sects and  fungous  diseases,  the  soap  in  this 
case  being  omitted.  Professor  Safro's 
work  further  shows  that  "Black  leaf  40" 
may  be  safely  combined  with  Bordeaux, 
and  the  desired  results  obtained.  Profes- 
sor Safro  writes  as  follows:  "For  pur- 
poses of  spraying  sweet  peas,  add  to  every 
100  gallons  of  Bordeaux  three-fourths  of 
a  pint  of  'Black  leaf  40.'  As  far  as  safety 
to  the  foliage  is  concerned,  much  greater 


SPRAYING  215 

strengths  of  nicotine  may  be  added  to  the 
Bordeaux,  but  no  additional  effectiveness 
will  be  given  to  the  mixture  as  an  insecti- 
cide. Any  nicotine  solution  that  is  used 
for  Aphis  containing  four-hundredths  of 
one  per  cent  nicotine  will  be  effective  if 
the  work  is  thoroughly  done." 

For  greenhouse  purposes  the  Auto  Spray 
No.  i  is  a  very  desirable  spraying  machine 
(fig.  43) .  It  may  also  be  used  outdoors  on 
small  garden  lots.  In  California,  where 
large  acreages  of  sweet  peas  are  grown  for 
seed,  a  gasoline  sprayer  is  the  proper  ma- 
chine. However,  as  the  plants  reach  three 
to  four  feet  and  as  the  rows  begin  to  touch, 
spraying  by  power  machinery  which  has  to 
be  drawn  by  horses  becomes  prohibitive. 
In  this  case  two  to  three  Auto  Sprays  No.  l 
will  answer  the  purpose  very  well. 


216    DISEASES  OF  THE  SWEET  PEA 

PRINCIPLES   INVOLVED   IN    SPRAYING 
SWEET    PEAS 

It  should  be  remembered  that  to  destroy 
chewing  insects  such  as  caterpillars,  etc., 
the  stomach  poison  must  be  evenly  dis- 
tributed all  over  the  plant.  This  should 
be  done  as  soon  as  the  presence  of  the  pest 
is  suspected.  Intelligent  and  observant 
growers  will,  of  course,  remember  the  time 
of  appearance  of  the  pest  every  year,  al- 
though the  time  depends  somewhat  on  the 
climate  of  each  season.  In  destroying  the 
green  aphids  the  contact  poison  should  be 
distributed  as  evenly  as  possible  on  the  in- 
sect itself.  It  is,  therefore,  best  to  spray 
for  aphids  as  they  are  actually  found 
working  on  the  plants.  With  chewing  in- 
sects and  with  fungous  pests,  however,  the 
applications  are  made  even  before  the  par- 
asites appear.  Before  spraying  it  is  nec- 
essary to  have  well  in  mind  the  organism 


SPRAYING  217 

which  is  to  be  destroyed,  and  the  proper 
ingredients  used.  To  keep  fungous  pests 
in  check  it  is  necessary  to  have  the  plant 
covered  with  the  fungicide  all  the  time 
infection  is  feared  or  suspected.  It  must 
be  remembered  that  spraying  for  fungi  is 
a  form  of  insurance.  It  protects  the  plant 
from  becoming  infected.  However,  when 
the  parasite  penetrates  the  host,  spraying 
is  of  little  value  in  saving  the  infected 
plant  although  it  will  protect  others  which 
are  as  yet  healthy.  It  is  essential  that  the 
sweet  pea  grower  be  ever  ready  to  spray 
on  time  (fig.  46) .  Sometimes  the  retarda- 
tion of  even  a  day  may  yield  negative  re- 
sults. The  timely  destruction  of  one  in- 
sect, or  of  one  spore,  undoubtedly  means 
the  destruction  of  countless  generations  of 
these  pests. 

Thoroughness  is  as  important  in  spray- 
ing as  it  is  in  everything  else  in  life.    Es- 


218    DISEASES  OF  THE  SWEET  PEA 

pecially  is  this  true  for  the  control  of 
fungous  diseases.  A  spore  accidentally 
lodged  on  a  portion  of  a  leaf  overlooked 
by  the  sprayer  is  like  a  fortified  city 
guarded  by  rusty  cannon. 

DIFFICULTIES  IN  THE  SPRAYING  OF 
SWEET  PEAS.  The  difficulties  in  spraying 
sweet  peas  is  that  the  average  fungicide 
will  not  stick.  This  is  especially  true 
where  coarse  nozzles  are  used;  the  liquid 
in  this  case  collects  into  large  drops  and 
then  rolls  off.  This  difficulty  is  eliminated 
by  the  use  of  very  fine  nozzles,  since  the 
finer  the  spray  the  greater  the  success. 
The  use  of  stickers  often  helps  to  make 
the  spray  liquid  adhere  better  to  the  foli- 
age. With  the  sweet  pea  the  use  of  soap 
answers  well  the  purpose  of  a  sticker. 
Add  two  to  three  pounds  of  soap  to  about 
every  100  gallons  of  the  spray  mixture 


CO 


fl      o 

'>>  g? 


f 


SPRAYING  219 

used.    Where  combination  sprays  are  used 
the  soap  is  to  be  omitted. 

SPRAYING  GREENHOUSE  SWEET  PEAS. 
Under  greenhouse  conditions,  insect  and 
fungous  pests  are  more  easily  controlled 
than  out  of  doors.  In  the  greenhouse,,  con- 
ditions are  more  nearly  under  the  control 
of  the  grower.  By  proper  cultural  care 
many  troubles  may  be  kept  in  check,  so  that 
spraying  may  be  dispensed  with.  There 
are,  however,  certain  days  when  the 
weather  is  such  that  proper  ventilation  is 
difficult  if  not  harmful.  The  greenhouse 
air  then  becomes  saturated  with  moisture, 
which  favors  the  development  of  mildew. 
At  other  times  the  house  is  allowed  to  get 
too  dry  and  red  spiders  and  aphids  make 
their  appearance.  Theoretically  red  spi- 
ders and  mites  may  be  controlled  by  fre- 
quent syringings  with  plain  water.  Prac- 


220    DISEASES  OF  THE  SWEET  PEA 

tically,  however,  the  syringing  is  not  al- 
ways done  in  the  proper  way  to  become 
effective.  In  this  case  spraying  with  a 
standard  contact  poison  becomes  necessary. 
Next  to  red  spiders,  the  only  insect  that  is 
of  economic  importance  is  the  green  aphid. 
Both  of  these  may  be  kept  in  check  by  the 
use  of  "Black  leaf  40,"  using  a  dilution  of 
one  part  to  one  thousand  (by  volume). 
Aphin  or  sulpho  tobacco  may  answer  the 
same  purpose.  Some  growers  prefer  the 
use  of  nico  fume  tobacco  papers.  With 
these  all  that  is  necessary  is  to  hang  the 
paper  on  any  convenient  nail  and  to  light 
the  end  of  it.  Should  mildew  appear  it 
may  be  readily  controlled  by  dusting  with 
flowers  of  sulphur,  or  by  spraying  with  po- 
tassium sulphide,  dissolving  four  ounces 
of  the  chemical  in  ten  gallons  of  water. 
The  solution  should  be  used  at  once,  as  it 
loses  its  strength  by  exposure  to  the  air. 


SPRAYING  221 

OUTDOOR  SPRAYING  OF  SWEET  PEAS. 
Under  our  present  conditions,  it  is  difficult 
to  raise  a  crop  of  sweet  peas  outdoors  with- 
out its  becoming  infested  with  most  of  the 
pests  enumerated  in  this  book.  Spraying 
therefore  becomes  a  necessity.  However, 
the  grower  cannot  afford  to  spray  for  each 
pest  separately.  A  combination  of  spray 
mixtures  becomes  imperative  so  that  one 
application  may  reach  at  the  root  of  many 
evils.  Red  spider,  the  green  aphid,  the 
chewing  insects,  as  well  as  the  fungous 
diseases  of  stems  and  leaves,  may  be  con- 
trolled by  a  combination  of  the  following 
materials  in  the  following  given  propor- 
tions : 

1.  Make  the  regular  5-5-50  Bordeaux 
formula. 

2.  If  the  green  aphid  is  present  add  to 
every  100  gallons  of  the  Bordeaux  three- 
fourths  of  a  pint  of  "Black  leaf  40." 


222    DISEASES  OF  THE  SWEET  PEA 

3.  To  each  100  gallons  of  1  and  2,  add 
l  Ib.  of  arsenate  of  lead  to  keep  in  check 
the  biting  insects.  If  Paris  green  is  used 
instead  of  arsenate  of  lead,  add  one  pound 
of  extra  lime  to  every  pound  of  the  above 
insecticide  used.  These  formulae  apply  to 
sweet  peas  grown  on  large  scales.  On 
smaller  plots,  such  as  the  home  garden,  the 
same  formulae  hold  good  except  that  cal- 
culations are  made  so  that  less  of  the  spray 
mixture  is  prepared  at  one  time. 

With  outdoor  sweet  peas,  spraying 
should  begin  as  soon  as  the  plants  are  six 
inches  high  and  should  be  continued  until 
the  plants  are  about  to  lose  their  useful- 
ness. The  frequency  of  the  applications 
will  depend  largely  on  the  weather.  The 
more  it  rains  the  more  often  spraying  is 
necessary.  The  object  should  be  to  keep 
the  plants  covered  a  large  part  of  the  grow- 


SPRAYING  223 

ing  period  with  spray  materials.  Under 
ordinary  conditions,  spraying  every  other 
week  is  a  desirable  practice. 


\ 


INDEX 


INDEX 


Acid  phosphate,  182 

Acid  soils,  25,  36 

Agrostis  neublosa,  58 

Alfalfa,  168,  169 

Alternaria,  178 

Ambrosia  sp.,  169 

American    Sweet    Pea    So- 
ciety, 6 

Ammonia,  211 

Ammoniacal     copper    car- 
bonate, 211 

Anthracnose,      137,      141, 
157,  176,  181 

Aphids,  142,  155,  157,  158 
161,  163 

Aphine,  208 

Aphelinus,  166 

Aphelinus  nigritus,  166 

Aphiduis,    162,    163,    165, 
166 

Aphiduis   testaceipes,    162, 
164 

Apple,  139 

Arachnida,  92 

Arsenate  of  lead,  207 

Arsenate  of  soda,  207 

Arsenicals,  207 

227 


Arsenate  of  zinc,  207 
Ascochyta  pisi,  151 
Auto  Spray  No.  1,  215 
Azaleas,  131 

Bacillus  lathy ri,  144 

Balanced  fertilizer,  182 

Beal,  A.  C.,  9,  104 

Beans,  134,  169 

Beets,  169 

Bench,  77 

Bisulphide  of  carbon,  180 

Blackberry,  wild,  134 

Black  blister  beetle,   169 

Black  leaf  40,  208,  214 

Black  leaf  40  and  lime  sul- 
phur, 214 

Black  leaf  40  and  arsenate 
of  lead,  214 

Black  leaf  40  and  arsenate 
of  zinc,  214 

Black  leaf  40  and  iron 
sulphate,  214 

Black  leaf  40  and  Bor- 
deaux, 214 

Blister  beetles,  168 

Blue  stone,  209 


228 


INDEX 


Bordeaux     mixture,     209, 

219 

Botrytis,  178 
Bod  drop,  181 

Camel's  hair  brush,  70 
Carnation,  89 
Caterpillars,  170 
Chaetomium  root  roc,  104- 

109 
Chaetomium         spirochaete, 

104 

Cheesedoth,  54 
Chrysopa  californka,  161 
Chittenden,  F.  J.,  112,  113, 

15*,  170 

Christmas  trade,  79 
Chrysanthemums,  89 
Clover,  168,  169 
Cleanliness,  198 
Climate,  63 
Clonostachys,  178 
Clump  method,  34,  45 
Cole,  12 

Collar  rot,  97,  119,  123 
Combination    sprays,    212, 

213 

Contact  poisons,  208 
Control  of  side  soils,  190, 

197 

Cooley,  R.  A,  213 
Copper  carbonate,  211 
Copper  sulphate,  209 
Cordon  system,  3$ 


Corn,  128,  169 
Cortidum  vagum,  98 
Cotton,  168 
Cow  pea,  115,  134 
Crab  grass,  128 
Crop  rotation,  199 
Cretan,  131 
Cucumber,  122 
Cultivation,  48 
Cultural 

196 

Culture  under  glass,  74 
Cupid  sweet  peas,  11,  12 
Cuthbertson,  F.  G.,  3$ 
Cut  worms,  202 

Dahlia,  131,  134 
Damping  off,  95,  96 
Mary,  3 
Uiabrotica     12     ponctata, 

167 

Diseased  seed,  176 
Dispodding,  49 
Downy  mildew  of  grapes, 

4 
Drug  store  beetle,  176 

Early  flowering,  21 
Eckford,  Henry,  11, 12,  14, 

46 

Ed  worm,  123 
Empusa  aphidis,  166,  167 
Epicauta      Pennsylvanica, 

169 


INDEX 


229 


Epicauta  vittata,  169 
Erisiphe  polygoni,  118 
Evaporation,  94 
Exhibiting,  $4,  55 

Fall  planting,  27,  28 
Ferns,  131 
Fertilizers,  76,  l8l 
Field  jforftrt,  135 
Rail,  69 

Flower  pathology,  5 
Formaldehyde,  189,  194 
Fungicides,  209 
Fusarium,  178 
Fusarium  lathyri,  109 
Fusarium    root    rot,    109- 
112 

Geranium,  wild,  134 
Glomerella    rnfomaculans, 

137»  181 

Grasshopper,  170 
Green  lace  wing,  161 
Grubs,   174 
Gysophila,58 

Hard  wood  ashes,  184 
Harris,  J.  E^  98 
Heliothrips        haHnorrhoi- 

dalis,  129 
Hellebore,  208 
Heterodera  radicicola,   123 
Hippodamia       convergens 

158 


History  of  the  sweet  pea, 

9 

Hollyhock  diseases,  6 
Honey  flies,  161 
Hntchins,  26 

Infected  areas,  196 
Infected  manure,  106 
Insect  pests,  152,  171 
Insecticides,  205 
Introduction,  1 
Irrigation,  72,  73 

Jamestown  weed,  134 
Johnson  grass,  128 
Judging,  72 

Kentucky  Product  Co.,  214 
Kerr,  G.  W.,  57 
Kew  Bulletin,  113 

Labeling,  35 
Lady  beetles,  158 
Lachnostcrna,  174 
Lathyrus  odoratus,  10 
Lathyrus  specks,  27 
Lettuce,  122 
Light,  97 
Lilies,  131 
Lime,  98,  209 
Lime  water,  21O 
lime  application,  25 
Litmus  paper,  98 

Macrosiphum  pisi,  152 


230 


INDEX 


Maggots,  160,  161 
Mangels,  169 
Manns,  T.  F.,  144 
Manure,  86,  199 
Manure  mulch,  28,  29 
Marketing,  51 
Market  varieties,  22 
Massee,  G.,  113,  118,  149 

151 

May  beetle,  174 
Melanotus  communis,  173 
Melons,  169 
Mendelian  principle,  69 
Metamorphosis,  92 
Methods  of  control,  185 
Microsphera  alni,  118 
Millardet,  M.,  4 
Mites,  92 
Moisture,  93,  94 
Morse,  C.  C.,  38,  60 
Mosaic,  141-144 
Mulching,  49 
Muriate  of  potash,  182 

Nematode  galls,  123 
Netting,  43,  44,  46,  47 
Nicotine,  215 
Nozzles,  218 

Orchid  flowering,  78,  84 

Packing,  53,  56 
Paper  boxes,  53 
Paris  green,  206,  207 


Parsnip,  115 
Parthenogenesis,  156 
Patterson,  Flora,  Mrs.,  105 
Pea  blight,  149-150 
Pea  spot,  151 
Peach  yellows,  143 
Perennial   rye  grass,   128 
Peridroma  saucia,  171 
Peronospora      trifoliorum, 

149,  151 

Peronospora  vicise,  150 
Philips,  W.  J.,  165 
Phlox,  131 
Physiological  diseases,  181- 

184 

Picking,  51,  52,  86 
Pink,  131 
Planting,  25,  31 
Pollination,  69,  70 
Potato,  169 

Potato  blight,  epidemic,  2 
Potassuim  sulphide,  21 1 
Powdery  mildew,  118,  119 
Preparation,  23,  27 

Radish,  169 

Rag  weed,  169 

Red  shell  soil,  75 

Red   spider,   92,    131-134, 

142-145 
Red  top,  128 
Resistant  varieties,  186 
Rhizoctonia   root  rot,   98- 

104 


INDEX 


231 


Rhizopus,  178 
Rogueing,  66,  67 
Rolfs,  F.  M.,  103 
Root  burn,  182 
Root  knot,  123-129 
Rye,  128,  168 

Sackett,  W.  G.,  99 

Safro,  Prof.,  214 

Sclerotinia  libertiana,   119 

Scorch  or  scald,  54 

Sclerotia,  122 

Seed,  25 

Seed  treatment,  35,  82,  188 

Selby,  A.  D.,  99 

Selection,  66,  67 

Shading,  54 

Shamel,  A.  D.,  193 

Shaw,  J.  F.  J.,  103 

Shriveled  seed,  177 

Site,  22 

Sitodrepa  panicea,  178 

Slow  germination,  26 

Soap,  218 

Soil  acidity,  98 

Soil  insects,  171 

Solid  beds,  76 

Sowing,  34,  35 

Sowing  in  pots,  34 

Spencer   varieties,    15,   6l, 

62,67 

Spraying,  204 
Spraying     formula,     221, 

222 


Spring  planting,  29 
Stackman,  E.  C.,  99 
Steam  sterilization,  191 
Stewart,  F.  C.,  1 18 
Stickers,  218 
Stomach  poisons,  206 
Streak,  7,  113,  157,  176 
String,  44,  45,  85 
Striped  blister  beetle,   169 
Sulpho  tobacco,  208 
Sulphur,  212 
Supports,  36,  37,  38,  40, 

41,  42,  44,  45,  46,  66, 

88 

Sweat  flies,  161 
Sweet    Pea    Annual,    39, 

112,  118,  149 
Swingle,  D.  B.,  213 
Syrphid  fly,  158,  160 
Syrphus  ribesii,  160 

Taubenhaus,  J.  J.,  141 
Temperature,   83,  84,   88, 

93.96 
Tetranchys      bimaculatus, 

131 

Thielavia  basicola,  112 
Thielavia  root  rot,  98,  1 12- 

117 

Thinning,  33 
Thrips,  129-131 
Tillage,  48 
Timothy,  128 
Tobacco,  115,  168 


232 


INDEX 


Tomato,  87,  88,  122,  133, 

134  m 

Transpiration,  94,  95 
Trench  method,  32 
Trial  ground,  71 
Triphleps  insidiosus,    133, 

134 

Turnip,  169 

Twelve   spotted   cucumber 
beetle,   167 

Variegated  cutworms,   171 

Varieties,    10,    12,    13,    14, 

15,   16,   17,   18,   19,  20, 

21,  22,  54,  55,  58,  78, 

79 
Vases,  52,  57,  59 


Ventilation,  36 
Verbena,  131 

Violets,  88,  89,   115,   122, 
133»  134 

Watering,  36,  37,  48,  49, 

81,  93.  94.  95 
Wax  paper,  53 
Webster,  F.  M.,  165 
White  grubs,  174,  202 
White  hellebore,  208 
Wind  currents,  93 
Wire,  85 
Wireworms,   173,   174 

Zinnia,    128 

Zvolanek,  A.  C.,  74,  78 


This  book  is  DUE  on  the  last  date  stamped  below 

OCT  3  0  193* 


2  ,  I93f 


B  sia  fr 


V 


OCT  3  9 


Form  L-9-15m-7,'31 


SB 

413         Taubenh.au  s  - 
S9T1       The  culture 
oop.l     and 

diseases  of 
the  sweet  pea. 


UNIVERSITY  of  CALIFORNIA 


